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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 649 records · Page 36
All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

A Multiscale Approach to Simulate Non‐Isothermal Multiphase Flow in Deformable Porous Materials

Coupled thermal, hydraulic, and mechanical processes in porous materials play important roles in several energy and environmental technologies. The Darcy-Brinkman-Biot (DBB) framework has proven effective in modeling multiphase fluid flow in deformable porous solids across both pore and Darcy scales, including in systems where fractures coexist with a porous matrix. In this study, we extend the DBB framework, originally designed for isothermal conditions, to address non-isothermal problems by incorporating an energy conservation equation. The resulting solver, hybridBiotThermalInterFoam, enables simulations of coupled multiphase fluid flow, heat transfer, and solid deformation in hybrid-scale systems containing both solid-free regions and ductile porous domains. The new solver is validated through comparisons with analytical solutions and, also, against established heat transfer solvers chtMultiRegionFoam and compressibleInterFoam. Further, a series of 2D and 3D case studies, including two-phase heat transfer in solid-free, static, or deformable porous media, highlights the solver's capacity to simulate complex flow dynamics and heat transport in systems involving high mobility ratios, viscous fingering, and fracture propagation. Our results establish the feasibility of incorporating thermal effects in simulations of a wide variety of energy geotechnics and environmental applications, including enhanced hydrocarbon recovery, soil remediation, and enhanced geothermal energy systems.

04 OIL SHALES AND TAR SANDS↗
DOE OSTI2025

A Finite Element Method for Compressible and Turbulent Multiphase Flow Instabilities with Heat Transfer

We present a new finite element framework for modeling compressible, turbulent multiphase flows with heat transfer. For two-fluid systems with a free surface, the Volume of Fluid (VOF) method is implemented without the need for interface reconstruction, while turbulence is resolved using a dynamic Vreman large eddy simulation (LES) model. Unlike most two-phase VOF studies, which neglect heat transfer, the present approach incorporates energy transport equations within the VOF formulation to account for heat exchange, an effect particularly important in turbulent flows. Conjugate heat transfer is often challenging in finite volume methods, which require explicit specification of heat fluxes at the solid–fluid interface, limiting accuracy and predictive capability. By contrast, the finite element formulation does not require heat flux inputs, allowing more accurate and robust simulation of heat transfer between solids and fluids. The method is demonstrated through three representative cases. First, a two-fluid instability with a single-mode perturbation is simulated and validated against analytical growth rates. Second, conjugate heat transfer is examined in a high-temperature flow over a cold metal cylinder, with validation performed both quantitatively—via pressure coefficient comparisons with experimental data—and qualitatively using vector field topology. Finally, compressible spray injection and breakup are modeled, demonstrating the ability of the framework to capture interfacial dynamics and atomization under turbulent, high-speed conditions. In the compressible spray injection and breakup case, the results indicate that the finite element formulation achieved higher predictive accuracy and robustness than the finite-volume method. With the same mesh resolution, the FEM reduced the root mean square error (RMSE) and mean absolute percentage error (MAPE) from 6.96 mm and 26.0% (for the FVM) to 4.85 mm and 12.7%, respectively, demonstrating improved accuracy and robustness in capturing interfacial dynamics and heat transfer. The study also introduced vector field topology to visualize and interpret coherent flow structures and instabilities, offering insights beyond conventional scalar-field analyses.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2024

Dependence of Uranium Oxide Polymorphism on Plasma Synthesis Conditions

Here, we synthesized uranium oxide nanoparticles using a plasma flow reactor (PFR) and studied the effects of three different experimental parameters on the resulting morphologies and speciation of the particles: (1) collection duration, (2) collection substrate temperature, and (3) radial collection position due to radial temperature gradients in the PFR. We also induced three distinct temperature histories along the axis of the plasma flow reactor by varying the gas flow rates downstream of the plasma torch. Transmission electron microscopy (TEM) analyses of collected particles showed two phases of uranium oxides (fcc-UO 2 and α-UO 3 ). The chemical compositions of the resulting uranium oxide particles were not altered by the three parameters investigated in this work but varied based on the temperature history induced. Preheating of the collection substrate led to deposition of fewer particles, which is attributed to a reduction in thermophoretic force caused by the reduced temperature gradient for preheated substrates. The relative amounts of UO 2 to UO 3 and particle size varied depending on the cooling history employed during synthesis.

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEA↗
DOE OSTI2017

Are continuum predictions of clustering chaotic?

Gas-solid multiphase flows are prone to develop an instability known as clustering. Two-fluid models, which treat the particulate phase as a continuum, are known to reproduce the qualitative features of this instability, producing highly-dynamic, spatiotemporal patterns. However, it is unknown whether such simulations are truly aperiodic or a type of complex periodic behavior. By showing that the system possesses a sensitive dependence on initial conditions and a positive largest Lyapunov exponent, λ 1 ≈1/τ, we provide a tentative answer: continuum predictions of clustering are chaotic. We further demonstrate that the chaotic behavior is dimensionally dependent, a conclusion which unifies previous results and strongly suggests that the chaotic behavior is not a direct consequence of the fundamental kinematic instability, but requires a secondary (inherently multidimensional) instability. Granular matter is a collection of discrete, interacting solid particles which, like classic (molecular) matter, can be generally classified into one of three states:1 (i) under static conditions granular heaps or piles can sustain gravity-induced stress and behave like a solid; (ii) dense granular flows characterized by enduring and multi-particle contacts behave similarly to a fluid; and (iii) rapid granular flows characterized by instantaneous contacts described as a granular gas. However, it is worth noting that all three granular states are only superficially similar to their molecular counterparts due to the dissipative nature of particle-particle contacts (inelasticity, friction, etc.). In industrial operations, rapid (collision-dominated) granular flows are often encountered in devices in which the particles are fluidized by a gas; such gas-solid flows are the focus of this work. Rapid gas-solid flows are prone to an instability termed clustering in which particles tend to form spatially inhomogeneous patterns of high and low concentrations. Continuum or two-fluid models (TFM) have long been known to be able to predict the qualitative nature of the clustering instability and more recent quantitative assessments have also shown promising results. However, it is yet unknown whether or not such predictions are chaotic. We take a first step in answering this question by simulating fluidization in an unbounded domain and calculating a positive largest Lyapunov exponent (LLE), thereby indicating that continuum predictions of clustering are in fact chaotic. Further, we show that chaotic behavior may be reduced to periodic behavior by constraining the dimensionality of the system.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
DOE OSTI2023

Numerical Study of Coupled Water and Vapor Flow, Heat Transfer, and Solute Transport in Variably-Saturated Deformable Soil During Freeze-Thaw Cycles

As climate change intensifies, soil water flow, heat transfer, and solute transport in the active, unfrozen zones within permafrost and seasonally frozen ground exhibit progressively more complex interactions that are difficult to elucidate with measurements alone. For example, frozen conditions impede water flow and solute transport in soil, while heat and mass transfer are significantly affected by high thermal inertia generated from water-ice phase change during the freeze-thaw cycle. To assist in understanding these subsurface processes, the current study presents a coupled two-dimensional model, which examines heat conduction-convection with water-ice phase change, soil water (liquid water and vapor) and groundwater flow, advective-dispersive solute transport with sorption, and soil deformation (frost heave and thaw settlement) in variably saturated soils subjected to freeze-thaw actions. This coupled multiphysics problem is numerically solved using the finite element method. The model's performance is first verified by comparison to a well-documented freezing test on unsaturated soil in a laboratory environment obtained from the literature. Then based on the proposed model, we quantify the impacts of freeze-thaw cycles on the distribution of temperature, water content, displacement history, and solute concentration in three distinct soil types, including sand, silt and clay textures. The influence of fluctuations in the air temperature, groundwater level, hydraulic conductivity, and solute transport parameters was also comparatively studied. The results show that (a) there is a significant bidirectional exchange between groundwater in the saturated zone and soil water in the vadose zone during freeze-thaw periods, and its magnitude increases with the combined influence of higher hydraulic conductivity and higher capillarity; (b) the rapid dewatering ahead of the freezing front causes local volume shrinkage within the non-frozen region when the freezing front propagates downward during the freezing stage and this volume shrinkage reduces the impact of frost heave due to ice formation. This gradually recovers when the thawed water replenishes the water loss zone during the thawing stage; and (c) the profiles of soil moisture, temperature, displacement, and solute concentration during freeze-thaw cycles are sensitive to the changes in amplitude and freeze-thaw period of the sinusoidal varying air temperature near the ground surface, hydraulic conductivity of soil texture, and the initial groundwater levels. Our modeling framework and simulation results highlight the need to account for coupled thermal-hydraulic-mechanical-chemical behaviors to better understand soil water and groundwater dynamics during freeze-thaw cycles and further help explain the observed changes in water cycles and landscape evolution in cold regions.

54 ENVIRONMENTAL SCIENCES↗
DOE OSTI2023

Pore-scale simulation of multiphase flow and reactive transport processes involved in geologic carbon sequestration

Multiphase flow and reactive transport are two essential physicochemical processes that govern the effectiveness of geological carbon sequestration (GCS). The interaction and feedback among different phases and components during intricate physicochemical processes hold great significance in understanding CO 2 sequestration. Pore-scale simulations can account for multiphase flow and reactive transport processes in porous media and obtain spatial distributions of parameters (density, velocity, concentration, etc.) in the pore space as well as their temporal evolutions. This proves especially valuable considering that experiments can be hindered by constraints in spatial and temporal resolution. The comprehensive insights garnered from pore-scale research can be leveraged for continuum modeling using the representative elementary volume (REV) concept. In this contribution, four sequential mechanisms of CO 2 -brine-rock interaction in three zones delineated by CO 2 saturation are elaborated to elucidate complicated physicochemical processes involved in GCS, which are followed by general descriptions of mathematical equations and pore-scale numerical methods. In addition, as interested and commonly encountered processes, leakage risks during GCS and CO 2 -enhanced oil recovery (CO 2 -EOR) processes are presented. The existing challenges and future directions are discussed for both the performance of the pore-scale models and the current gaps in the field of GCS. Importantly, we expect that this review will prove beneficial for researchers interested in pore-scale simulations, GCS, and related disciplines.

58 GEOSCIENCES↗
DOE OSTI2015

Experimental analysis of spatial correlation effects on capillary trapping of supercritical CO 2 at the intermediate laboratory scale in heterogeneous porous media

Several numerical studies have demonstrated that the heterogeneous nature of typical sedimentary formations can favorably dampen the accumulation of mobile CO 2 phase underneath the caprock. Core flooding experiments have also shown that contrasts in capillary entry pressure can lead to buildup of nonwetting fluid phase (NWP) at interfaces between facies. Explicit representation of geological heterogeneity at the intermediate (cm-to-m) scale is a powerful approach to identify the key mechanisms that control multiphase flow dynamics in porous media. The ability to carefully control flow regime and permeability contrast at a scale that is relevant to CO 2 plume dynamics in saline formations offers valuable information to understand immiscible displacement processes and provides a benchmark for mathematical models. To provide insight into the impact of capillary heterogeneity on flow dynamics and trapping efficiency of supercritical CO 2 under successive drainage and imbibition conditions, we present an experimental investigation conducted in a synthetic sand reservoir. By mimicking the interplay of governing forces at reservoir conditions via application of surrogate fluids, we performed three immiscible displacement experiments to observe the entrapment of NWP in heterogeneous porous media. Capillary trapping performance is evaluated for each scenario through spatial and temporal variations of NWP saturation; for this reason we adopted X-ray attenuation to precisely measure phase saturation throughout the flow domain and apply spatial moment analysis. Furthermore, the sweeping performance of two different permeability fields with comparable variance but distinct spatial correlation was compared against a homogeneous base case with equivalent mean permeability by means of spatial moment analysis.

58 GEOSCIENCES↗
DOE OSTI2022

Modeling the viscoplastic behavior of a semicrystalline polymer

In this study, a complex constitutive relation is identified using inverse modeling with the nominal mechanical response as sole experimental input. The methodology is illustrated for a semicrystalline thermoplastic in the presence of strain localization at finite deformations. The experimental database includes cylindrical tensile bars, compression pins and round notched bars loaded at strain rates spanning up to five decades and temperatures below and above T g . The data is organized into a calibration set and a validation set. The response of tensile specimens is determined using finite element analyses and a two-phase constitutive relation for semicrystalline polymers that accounts for temperature- and rate-sensitive plastic flow, pressure-sensitivity, small-strain softening and large-strain orientational hardening of the amorphous phase, along with the evolution of crystallinity. The large number of constitutive parameters is identified using an optimization tool coupled with the finite element solver and the calibration set from experiments. The methodology is shown to be successful in predicting the response of round notched bars and replicating the effects of temperature and strain rate on the severity of necking in tensile bars. The proposed model identification strategy is both simple and effective in comparison with other elaborate methods that attempt to access intrinsic behavior directly from high-fidelity experimental measurements.

36 MATERIALS SCIENCE↗
DOE OSTI2019

Mercury Remediation in Oak Ridge, Tennessee; Successes and Remaining Challenges

Mercury remediation is a high priority for the US Department of Energy’s (DOE’s) Environmental Management program in Oak Ridge, Tennessee because of large historical losses of mercury to the environment, and the potential health risks to humans and wildlife primarily through fish consumption. Remedial solutions for mercury contaminated aquatic systems are limited – many aquatic systems have diffuse sources of mercury (Hg) and depending on the environmental conditions, these low concentrations of inorganic Hg can result in fish consumption advisories due to the production of the more toxic methylmercury (MeHg) and its bioaccumulation and biomagnification. From the 1980s to the present, long-term monitoring of mercury concentrations in water and fish downstream of DOE facilities in Oak Ridge have provided an opportunity to assess the performance and effectiveness of various remedial and abatement actions to address mercury. Early actions in the mid-1980s focused on pollution control that positively affected mercury discharges to one local stream, including consolidation and elimination of untreated discharges, sanitary sewer relining, the construction of a pollution control facility, and the replacement of a contaminated settling basin. The 1990s were an intensive period of facility remedial actions designed to improve stream water quality and reduce mercury discharges. Actions included dechlorinating cooling water discharges, an additional phase of storm sewer relining, the addition of flow from a nearby reservoir, the addition of two small-scale mercury treatment systems, the bypass of stream flow around the settling basin, and the removal of high mercury-contaminated floodplain soils. Because of these multiple remedial actions total mercury concentrations in receiving streams decreased significantly; however, mercury concentrations in fish did not respond commensurately and remain a challenge to the present day. Although the mercury remedial strategy in Oak Ridge will continue to focus in the near-term on upstream facility source reduction, recent research suggests that understanding mercury transport, methylation, and bioaccumulation processes in the downstream environment is essential to reducing mercury fish concentrations. Since 2014, mercury remediation research and technology development activities have been underway to develop potential remedial solutions for the downstream environment, including use of sorbents to control soil leaching and the potential use of chemical or biological manipulations. The Oak Ridge mercury remediation story is a valuable case study for flowing systems that can inform our national-level understanding of potential mercury cleanup actions and their likely environmental response.

Peterson, Mark J.↗
DOE OSTI2019

Mercury Remediation in Oak Ridge, Tennessee; Successes and Remaining Challenges - 19390

Mercury remediation is a high priority for the US Department of Energy's (DoE's) Environmental Management program in Oak Ridge, Tennessee because of large historical losses of mercury to the environment, and the potential health risks to humans and wildlife primarily through fish consumption. Remedial solutions for mercury contaminated aquatic systems are limited - many aquatic systems have diffuse sources of mercury (Hg) and depending on the environmental conditions, these low concentrations of inorganic Hg can result in fish consumption advisories due to the production of the more toxic methylmercury (MeHg) and its bioaccumulation and biomagnification. From the 1980's to the present, long-term monitoring of mercury concentrations in water and fish downstream of DOE facilities in Oak Ridge have provided an opportunity to assess the performance and effectiveness of various remedial and abatement actions to address mercury. Early actions in the mid-1980's focused on pollution control that positively affected mercury discharges to one local stream, including consolidation and elimination of untreated discharges, sanitary sewer relining, the construction of a pollution control facility, and the replacement of a contaminated settling basin. The 1990's were an intensive period of facility remedial actions designed to improve stream water quality and reduce mercury discharges. Actions included dechlorinating cooling water discharges, an additional phase of storm sewer relining, the addition of flow from a nearby reservoir, the addition of two small-scale mercury treatment systems, the bypass of stream flow around the settling basin, and the removal of high mercury-contaminated floodplain soils. Because of these multiple remedial actions total mercury concentrations in receiving streams decreased significantly; however, mercury concentrations in fish did not respond commensurately and remain a challenge to the present day. Although the mercury remedial strategy in Oak Ridge will continue to focus in the near-term on upstream facility source reduction, recent research suggests that understanding mercury transport, methylation, and bioaccumulation processes in the downstream environment is essential to reducing mercury fish concentrations. Since 2014, mercury remediation research and technology development activities have been underway to develop potential remedial solutions for the downstream environment, including use of sorbents to control soil leaching and the potential use of chemical or biological manipulations. The Oak Ridge mercury remediation story is a valuable case study for flowing systems that can inform our national-level understanding of potential mercury cleanup actions and their likely environmental response. (authors)

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2016

Development of a Thin Film Primary Surface Heat Exchanger for Advanced Power Cycles

This project objective is to develop a high-temperature design upgrade for an existing primary surface heat exchanger so that the redesigned hardware is capable of operation in CO 2 at temperatures up to 1,510°F (821°C) and pressure differentials up to 130 psi (9 bar). The heat exchanger is proposed for use as a recuperator in an advanced low-pressure oxy-fuel Brayton cycle that is predicted to achieve over 50% thermodynamic efficiency, although the heat exchanger could also be used in other high-temperature, low-differential pressure cycles. This report describes the progress to date, which includes continuing work performed to select and test new candidate materials for the recuperator redesign, final mechanical and thermal performance analysis results of various redesign concepts, and the preliminary design of a test loop for the redesigned recuperator including a budgetary estimate for detailed test loop design, procurement, and test operation. A materials search was performed in order to investigate high-temperature properties of many candidate materials, including high-temperature strength and nickel content. These properties were used to rank the candidate materials, resulting in a reduced list of nine materials for corrosion testing. Multiple test rigs were considered and analyzed for short-term corrosion testing and Thermal Gravimetric Analysis (TGA) was selected as the most cost-effective option for evaluating corrosion resistance of the candidate materials. In addition, tantalum, niobium, and chromium coatings were identified as potential options for increased corrosion resistance. The test results show that many materials exhibit relatively low weight gain rates, and that niobium and tantalum coatings may improve corrosion resistance for many materials, while chromium coatings appear to oxidize and debond quickly. Metallurgical analysis of alloys was also performed, showing evidence of intergranular attack in 282 that may cause long-term reliability problems in CO 2 service at these temperatures. However, long-term testing in a flowing environment is recommended in order to understand accurately the severity of the attack. Detailed economic modeling of the existing air cycle recuperator and CO 2 cycle recuperator options was also completed, including costs for material, fabrication, fuel, maintenance, and operation. The analysis results show that the increased capital cost for high-temperature materials may be offset by higher cycle efficiencies, decreasing the overall lifetime cost of the system. The economic analysis also examines costs associated with increased pressure drop and material changes for two redesign options. These results show that, even with slightly reduced performance and/or higher material costs, the lifetime cost per energy production may still be reduced by over 12%. The existing recuperator design information was provided by Solar Turbines, Inc. via several models, drawings, and design handoff meetings. Multiple fluid/thermal and structural models were created in order to analyze critical recuperator performance and mechanical strength in critical areas throughout the redesign process. These models were analyzed for a baseline condition (consistent with current Mercury 50 operation) for validation purposes. Results are presented for heat transfer coefficients and pressure drops, matching well with the existing operational data. Simulation of higher-temperature CO 2 conditions was also performed, showing a slight expected increase in both heat transfer and pressure drop. Mechanical analysis results for critical areas on the cross-flow and counter-flow sheets have also been obtained for air and CO 2 cases. These results show similar stresses in both cases but significantly reduced safety factors for the CO 2 case due to reduced yield and creep rupture strengths of alloy 625 at the higher temperatures. A concept brainstorm session and initial down-selection were completed in order to identify promising redesign options for further analysis. Detailed analysis of all promising redesign options was performed via finite element and computational fluid dynamic simulations in order to characterize mechanical and thermal-fluid performance of each option. These options included material change, various sheet thickness configurations, pitch and phasing of cross-flow and counter-flow sheets, and separator sheets. The analysis results have identified two viable redesign options that maintain existing safety margins optimally through a material change to Haynes 282 and (A) sheet thickness increases of 40% on the counter-flow sheet and 75% on the hot side cross-flow corrugation sheet or (B) addition of a separator sheet in the counter-flow section while maintaining the original counter-flow sheet thickness and increasing the cross-flow corrugation sheet thickness by 90% to account for the increase in cell height. While both options satisfy mechanical stress constraints, the separator sheet design has a higher part count, slightly reduced heat transfer, and slightly higher pressure drop than the first option and is not preferred. Finally, several test loop concepts have been developed for different full-scale and reduced-scale recuperator testing options. For each option, various loop components, such as heat exchangers, valves, heaters, and compressors, were evaluated in an effort to maximize utilization of existing resources. All concepts utilize an existing 3-MW CO 2 compressor, heater, and loop coolers, but the concepts vary by incorporating different amounts of new equipment for achieving various flow rates (all concepts operate at design pressure and temperature). The third concept achieves a 1 kg/s test without purchasing any costly equipment (coolers, heaters, blowers, etc.). Since the stacked cell design of the recuperator results in the same flow conditions at each core cell (even for a reduced-scale test). Thus, test loop Concept #3 was selected for the preliminary design. This loop design is detailed within the report, culminating in a budgetary estimate of $1,013,000.00 for the detailed design, construction, commissioning, and operation of a high-temperature recuperator test loop.

03 NATURAL GAS↗
DOE OSTI2015

Catalyst synthesis and evaluation using an integrated atomic layer deposition synthesis–catalysis testing tool

An integrated atomic layer deposition-catalysis (I-ALD-CAT) tool was developed, combining an ALD manifold with a plug-flow reactor system for the synthesis of supported catalytic materials by ALD and immediate evaluation of catalyst reactivity using gas-phase probe reactions. The I-ALD-CAT system can deliver gaseous reagents comprised of 12 different metal ALD precursors, 4 oxidizing or reducing agents, and 4 catalytic reaction feeds to either of the two plug-flow reactors. The system can employ reactor pressures and temperatures in the range of 10 -3 to 1 bar and 300–1000 K, respectively. Furthermore, the instrument is also equipped with a gas chromatograph and a mass spectrometer unit for the detection and quantification of volatile species from ALD and catalytic reactions. In this report, we demonstrate the use of the I-ALD-CAT tool for the ALD of platinum active sites and Al 2 O 3 overcoats, and evaluation of catalyst propylene hydrogenation activity.

47 OTHER INSTRUMENTATION↗
DOE OSTI2024

High Temperature Additive Architectures for 65% Efficiency (Final Technical Report)

This project aimed to develop advanced high-temperature additive components that contribute towards the DOE’s goal for advanced gas turbines that are capable of at least 65% efficiency in combined cycle application. The objective was to leverage state-of-the-art additive manufacturing to develop an innovative stage 1 turbine nozzle (S1N) that can provide cooling flow savings while maintaining the component durability expected in today’s gas turbines. The program had two phases. Phase I was a conceptual phase for novel advanced cooling designs enabled by additive manufacturing, as well as proposals for validation. Phase II included execution of the Phase I conceptual design, including manufacturing of prototype hardware and validation within an environment that is similar to engine operation. During Phase I of the program, the team devised a concept to reduce cooling air usage. The cooling air used in the side walls is filmed out along the side walls, while the cooling air used in the airfoil is eventually directed to near-wall channels and exits holes along the airfoil trailing end. During this program, the team performed additive trials to analyze the geometric limitations of additive manufacturing. This helped the team understand minimum wall thicknesses, hole sizes, and cooling channel dimensions among other limits. Phase II of this program pushed GE Vernova beyond its previous experience of designing and manufacturing an additively manufactured hot gas path component. Modern hot gas path components utilize material chemistries that are traditionally hard to weld, such as cast Renè 108, and exhibit solidification cracking when additively manufactured using Direct Metal Laser Melting (DMLM). Note that AM108 is a powder form of Renè 108. A S1N with advanced cooling is larger and more complex than parts previously built by additive manufacturing and required new learnings to resolve risks around solidification cracking. Finally, the team validated the design in a combustion rig that replicated operation in a gas turbine. In order to properly quantify the benefits of the new additive design, a baseline was also tested in the rig and operated under the same conditions. In addition, an uncertainty analysis was done to quantify any sources of error that could impact the results. At the end of the validation effort, it was determined that the additive nozzle exceeded the 15% reduction in cooling flow goal even with the worst-case assumptions for uncertainty.

03 NATURAL GAS↗
DOE OSTI2018

Oil effect on CO 2 foam stabilized by a switchable amine surfactant at high temperature and high salinity

Despite the possible detrimental effect of oil on foam displacement processes in CO 2 EOR the effect of oil on dense CO 2 foams has received little attention relative to air foams or low density CO 2 foams. Herein, the effect of both a first contact miscible hydrocarbon (dodecane) and crude oil on CO 2 /water (C/W) foams generated by a switchable surfactant, C 12–14 N(EO) 2 was examined at dense CO 2 conditions at temperatures up to 120 °C (393 K) and 3400 psia (23 MPa). Upon increasing the fractional flow of dodecane, a gradual decrease in foam viscosity was observed as the foam becomes unstable. Since only two phases are present, traditional destabilization mechanisms for three phase oil/gas/water systems based on the entering and spreading are invalid. Therefore, an alternative mechanism is suggested whereby added dodecane strengthen the surfactant tail interactions with the nonaqueous phase (mixture of CO 2 and dodecane) to shift the hydrophilic-CO 2 philic balance (HCB) towards an unstable region. This mechanism is supported by a decrease of the CO 2 –water interfacial tension from ~5 mN/m to 0.5 mN/m for dodecane–water systems at 120 °C and 3400 psia. The effect of crude oil was more profound than for dodecane, whereby rapid destabilization of foam occurred at an oil fractional flow as low as 0.2. In this case, the immiscible portion of the crude oil can enter and spread at the lamellae to destabilize the foam as is evident in positive entering and spreading coefficients. Also, other foam destabilizing parameters such as temperature and capillary pressure were studied in the presence of oil and the results were consistent with those in the absence of oil.

nuclear (including radiation effects), carbon sequ↗
DOE OSTI2020

The MFiX Particle-in-Cell Method (MFiX-PIC) Theory Guide

MFiX (Multiphase Flow with Interphase eXchanges) is an open-source multiphase flow solver developed at the National Energy Technology Laboratory. Within the code, users have access to a single phase or interpenetrating continua-based multiphase two-fluid model (TFM), a discrete element model (DEM), and a particle-in-cell model (PIC). TFM, DEM, and PIC can all be used to create multiphase simulations that include hydrodynamics, chemical reactions, and heat transfer.

01 COAL, LIGNITE, AND PEAT↗
DOE OSTI2016

Efficient implicit LES method for the simulation of turbulent cavitating flows

We present a numerical method for efficient large-eddy simulation of compressible liquid flows with cavitation based on an implicit subgrid-scale model. Phase change and subgrid-scale interface structures are modeled by a homogeneous mixture model that assumes local thermodynamic equilibrium. Unlike previous approaches, emphasis is placed on operating on a small stencil (at most four cells). The truncation error of the discretization is designed to function as a physically consistent subgrid-scale model for turbulence. We formulate a sensor functional that detects shock waves or pseudo-phase boundaries within the homogeneous mixture model for localizing numerical dissipation. In smooth regions of the flow field, a formally non-dissipative central discretization scheme is used in combination with a regularization term to model the effect of unresolved subgrid scales. The new method is validated by computing standard single- and two-phase test-cases. Comparison of results for a turbulent cavitating mixing layer obtained with the new method demonstrates its suitability for the target applications.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2025

Active Fluids Form System-Spanning Filamentary Networks

Recent experimental realizations of liquid-liquid phase separation of active liquid crystals have offered an insight into the interaction between phase separation, ubiquitous in soft matter and biology, and chaotic active flows. Here, in this Letter, we use continuum theory to examine phase separation of an active liquid crystal and a passive fluid and report two new results. First, we provide an analytical derivation of the activity-induced suppression of the phase boundary of the coexistence region—a result first reported in simulations and experiments. We show that the shift in the critical point is a result of the balance between self-stirring active flows and phase-separating diffusive fluxes. Second, we show that this same balance is responsible for dramatically changing the morphology of the phase separated state, resulting in the emergence of a new mixed active phase consisting of a dynamical filamentous active network that invades the entire system area, trapping droplets of passive material. This structure exists even for very low volume fractions of active material. Our work provides an important step towards the goal of understanding how to use activity as a new handle for sculpting interfaces.

active nematics↗
DOE OSTI2021

Biocatalytic Yarn for Peroxide Decomposition with Controlled Liquid Transport

In this study, a robust biocatalytic yarn with controllable liquid transport properties is created by coating thin layers of chitosan containing catalase onto a cellulosic yarn. The resulting material integrates enzyme catalytic functionality with protective coating properties of chitosan and structural functionality of the textile. Mild immobilization conditions and good affinity between the two polysaccharides minimize enzyme inactivation during the preparation steps and prevent enzyme from leaching during peroxide decomposition testing and washing, providing a novel and versatile enzyme immobilization strategy. The catalytic efficiency of enzymes in a reaction containing solid, liquid, and gas phases is facilitated when dissolved enzyme substrate is transported by liquid flowing through the coated textile structure. The flow-through configuration decomposes at least two times more peroxide in a twenty-times smaller reaction zone volume compared to a stirred tank configuration. Liquid transport through the yarn and liquid spatial distribution within the yarn are investigated by in situ neutron radiography and neutron computed tomography, revealing a constrained wicking mechanism that benefits biocatalytic yarn performance. This new class of sustainable and flexible biocatalytic textile matrices has beneficial multifunctional properties, not previously described, that are applicable for numerous small- and large-scale applications including controlled flow reactors and reactive filtration.

36 MATERIALS SCIENCE↗