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Results for “SOLAR MODELING”

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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Development of a global 3-D magnetohydrodynamic computational model for solar wind/cometary and planetary studies

Progress is reported in the development of a global, 3-D magnetohydrodynamic computational model to quantitatively describe the detailed continuum field and plasma interaction process of the solar wind with cometary and planetary magneto/ionopause shapes. Activities described include enhancements to the present Level 1 model, development of the 3-D gas dynamic flow field solvers for the Level 2 model, and continued development of the 3-D frozen magnetic field solver for the Level 2 model.

Stahara, S. S.↗
DOE OSTI2012

THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC MODELING OF THE SOLAR WIND INCLUDING PICKUP PROTONS AND TURBULENCE TRANSPORT

To study the effects of interstellar pickup protons and turbulence on the structure and dynamics of the solar wind, we have developed a fully three-dimensional magnetohydrodynamic solar wind model that treats interstellar pickup protons as a separate fluid and incorporates the transport of turbulence and turbulent heating. The governing system of equations combines the mean-field equations for the solar wind plasma, magnetic field, and pickup protons and the turbulence transport equations for the turbulent energy, normalized cross-helicity, and correlation length. The model equations account for photoionization of interstellar hydrogen atoms and their charge exchange with solar wind protons, energy transfer from pickup protons to solar wind protons, and plasma heating by turbulent dissipation. Separate mass and energy equations are used for the solar wind and pickup protons, though a single momentum equation is employed under the assumption that the pickup protons are comoving with the solar wind protons. We compute the global structure of the solar wind plasma, magnetic field, and turbulence in the region from 0.3 to 100 AU for a source magnetic dipole on the Sun tilted by 0 Degree-Sign -90 Degree-Sign and compare our results with Voyager 2 observations. The results computed with and without pickup protons are superposed to evaluate quantitatively the deceleration and heating effects of pickup protons, the overall compression of the magnetic field in the outer heliosphere caused by deceleration, and the weakening of corotating interaction regions by the thermal pressure of pickup protons.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS2012

Three-Dimensional Magnetohydrodynamic Modeling of the Solar Wind Including Pickup Protons and Turbulence Transport

To study the effects of interstellar pickup protons and turbulence on the structure and dynamics of the solar wind, we have developed a fully three-dimensional magnetohydrodynamic solar wind model that treats interstellar pickup protons as a separate fluid and incorporates the transport of turbulence and turbulent heating. The governing system of equations combines the mean-field equations for the solar wind plasma, magnetic field, and pickup protons and the turbulence transport equations for the turbulent energy, normalized cross-helicity, and correlation length. The model equations account for photoionization of interstellar hydrogen atoms and their charge exchange with solar wind protons, energy transfer from pickup protons to solar wind protons, and plasma heating by turbulent dissipation. Separate mass and energy equations are used for the solar wind and pickup protons, though a single momentum equation is employed under the assumption that the pickup protons are comoving with the solar wind protons.We compute the global structure of the solar wind plasma, magnetic field, and turbulence in the region from 0.3 to 100 AU for a source magnetic dipole on the Sun tilted by 0 deg - .90 deg and compare our results with Voyager 2 observations. The results computed with and without pickup protons are superposed to evaluate quantitatively the deceleration and heating effects of pickup protons, the overall compression of the magnetic field in the outer heliosphere caused by deceleration, and the weakening of corotating interaction regions by the thermal pressure of pickup protons.

Usmanov, Arcadi V.↗
DOE OSTI2017

Use of MERRA-2 in the National Solar Radiation Database and Beyond

The National Solar Radiation Database (NSRDB) is a flagship product of NREL that provides solar radiation and ancillary meteorological information through a GIS based portal. This data is provided at a 4kmx4km spatial and 30 minute temporal resolution covering the period between 1998-2015. The gridded data that is distributed by the NSRDB is derived from satellite measurements using the Physical Solar Model (PSM) that contains a 2-stage approach. This 2-stage approach consists of first retrieving cloud properties using measurement from the GOES series of satellites and using that information in a radiative transfer model to estimate solar radiation at the surface. In addition to the satellite data the model requires ancillary meteorological information that is provided mainly by NASA's Modern Era Retrospecitve Analysis for Research and Applications (MERRA-2) 2 model output. This presentation provides an insight into how the NSRDB is developed using the PSM and how the various sources of data including the MERRA-2 data is used during the process.

14 SOLAR ENERGY↗
NASA NTRS1980

Numerical models of solar modulation of galactic cosmic rays, including drifts

Numerical solutions are presented of the steady-state modulation of galactic cosmic rays for a realistic two-dimensional model which includes drifts. Calculations of energy spectra and the spatial density variation of protons are shown for a model that incorporates the solar-minimum magnetic field and nominal interplanetary propagation parameters. The calculated values are relatively insensitive to the assumed size of the modulating region and to the magnitude of the particle diffusion coefficient. The solutions show a broad interior 'plateau' in which radial gradients are small. A simple model that neglects diffusion but includes drifts and adiabatic cooling accounts for these results. It is concluded that in this model and the range of parameters, diffusion plays a role secondary to that of drifts and adiabatic cooling.

Jokipii, J. R.↗
NASA NTRS1981

A model of solar flux attenuation during eclipse passage and its effects on photoelectron emission from satellite surfaces

The basic theory of solar flux attenuation by the earth's atmosphere is reviewed and a model of the time-varying flux observed by a satellite during eclipse passage developed. The general model is applied to the specific problem of variations in photoelectron flux during penumbral passage and the effects of wavelength, solar activity, and atmospheric constituents on photoelectron emission investigated. Predictions of the photoelectron current expected from tungsten and aluminum surfaces are then successfully compared with actual observations from the ATS-5 and Injun 5 satellites confirming the validity of the model.

Garrett, H. B.↗
DOE OSTI2013

A GRID OF THREE-DIMENSIONAL STELLAR ATMOSPHERE MODELS OF SOLAR METALLICITY. I. GENERAL PROPERTIES, GRANULATION, AND ATMOSPHERIC EXPANSION

Present grids of stellar atmosphere models are the workhorses in interpreting stellar observations and determining their fundamental parameters. These models rely on greatly simplified models of convection, however, lending less predictive power to such models of late-type stars. We present a grid of improved and more reliable stellar atmosphere models of late-type stars, based on deep, three-dimensional (3D), convective, stellar atmosphere simulations. This grid is to be used in general for interpreting observations and improving stellar and asteroseismic modeling. We solve the Navier Stokes equations in 3D and concurrent with the radiative transfer equation, for a range of atmospheric parameters, covering most of stellar evolution with convection at the surface. We emphasize the use of the best available atomic physics for quantitative predictions and comparisons with observations. We present granulation size, convective expansion of the acoustic cavity, and asymptotic adiabat as functions of atmospheric parameters.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2023

Bringing Low- and Moderate-Income Solar Financing Models to Scale (Final Technical Report (FTR))

In this final report, the Clean Energy States Alliance(CESA) and its project partners describe their work to accelerate the development of solar projects for three distinct subsets of the low- to moderate-income(LMI) solar market: single-family homes, manufactured homes, and community institutions, including multifamily affordable housing. For each market sector, the project team undertook research, outreach, and market-building activities. By advancing promising LMI solar financing innovations for different housing types and spreading them to new locations, the Scaling Up Solar for Under-Resourced Communities project has built momentum to scale up LMI solar. Although the report describes some research pertaining to solar adoption in LMI communities, this project was original in that it focused on two specific models to tackle single-family homes and community institutions. Until this project, very little research dedicated to solar for manufactured homes existed. For each market sector, the project team undertook research, outreach, and market-building activities. For the single-family homes sector, the project encouraged states to adapt a program model based on a successful Connecticut initiative that has brought solar to thousands of LMI homeowners. For manufactured homes, the project analyzed the potential for using solar for that housing sector and worked with states, utilities, and other stakeholders to launch pilot projects or programs. For community institutions, the project team worked with foundations, lenders, and community service organizations to inventory, analyze, and communicate models for philanthropic investment that accelerate the deployment of solar and solar+storage in multifamily affordable housing, health centers, and other LMI-serving community institutions.

14 SOLAR ENERGY↗
DOE OSTI2017

A Multiple Flux-tube Solar Wind Model

We present a new model, MULTI-VP, which computes the three-dimensional structure of the solar wind and includes the chromosphere, the transition region, and the corona and low heliosphere. MULTI-VP calculates a large ensemble of wind profiles flowing along open magnetic field lines that sample the entire three-dimensional atmosphere or, alternatively, a given region of interest. The radial domain starts from the photosphere and typically extends to about 30 R{sub ⊙}. The elementary uni-dimensional wind solutions are based on a mature numerical scheme that was adapted in order to accept any flux-tube geometry. We discuss here the first results obtained with this model. We use Potential Field Source-surface extrapolations of magnetograms from the Wilcox Solar Observatory to determine the structure of the background magnetic field. Our results support the hypothesis that the geometry of the magnetic flux-tubes in the lower corona controls the distribution of slow and fast wind flows. The inverse correlation between density and speed far away from the Sun is a global effect resulting from small readjustments of the flux-tube cross-sections in the high corona (necessary to achieve global pressure balance and a uniform open flux distribution). In comparison to current global MHD models, MULTI-VP performs much faster and does not suffer from spurious cross-field diffusion effects. We show that MULTI-VP has the capability to predict correctly the dynamical and thermal properties of the background solar wind (wind speed, density, temperature, magnetic field amplitude, and other derived quantities) and to approach real-time operation requirements.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

A solar-wind model including proton thermal anisotropy.

A relatively simple model is proposed to study the magnetohydrodynamic expansion of the solar wind. The interplanetary space is divided into an 'inner region' and an 'outer region.' In the inner region the solar wind is one-fluid and thermally isotropic. The solar-wind protons are assumed to be completely collisionless in the outer region. Thus the solar wind is two-fluid in nature, and the protons are thermally anisotropic in the outer region. It is assumed that throughout the interplanetary space electrons are thermally isotropic due to collisions or other processes. The electron heat flux is supposed to obey the well-known relationships that the flux is parallel to the magnetic-field vector and is directly proportional to the spatial derivative of the electron temperature.

Whang, Y. C.↗
NASA NTRS1989

Numerical model of solar dynamic radiator for parametric analysis

Growth power requirements for Space Station Freedom will be met through addition of 25 kW solar dynamic (SD) power modules. Extensive thermal and power cycle modeling capabilities have been developed which are powerful tools in Station design and analysis, but which prove cumbersome and costly for simple component preliminary design studies. In order to aid in refining the SD radiator to the mature design stage, a simple and flexible numerical model was developed. The model simulates heat transfer and fluid flow performance of the radiator and calculates area mass and impact survivability for many combinations of flow tube and panel configurations, fluid and material properties, and environmental and cycle variations.

Rhatigan, Jennifer L.↗
NASA NTRS1995

A global 3-D MHD model of the solar wind with Alfven waves

A fully three-dimensional solar wind model that incorporates momentum and heat addition from Alfven waves is developed. The proposed model upgrades the previous one by considering self-consistently the total system consisting of Alfven waves propagating outward from the Sun and the mean polytropic solar wind flow. The simulation region extends from the coronal base (1 R(sub s) out to beyond 1 AU. The fully 3-D MHD equations written in spherical coordinates are solved in the frame of reference corotating with the Sun. At the inner boundary, the photospheric magnetic field observations are taken as boundary condition and wave energy influx is prescribed to be proportional to the magnetic field strength. The results of the model application for several time intervals are presented.

Usmanov, A. V.↗
NASA NTRS1987

Steady state flow/field model of solar wind interaction with Venus - Global implications of local effects

Physical and chemical processes in the Venus ionosphere driven by the interaction of the solar wind with the atmosphere of Venus are described, and a model describing the interrelationships of these processes in a self-consistent manner is formulated. It is shown that the magnetic field configuration of the ionosphere is a steady state global structure which results from a combination of a large-scale 'open' current system connecting through the ionopause to the postshock solar wind and two small-scale 'closed' current systems entirely confined within the ionosphere and generated by ionospheric flows and shears. A previously detected ionospheric layer in O2(+) near 170 km altitude is shown to be a new type of ionospheric layer resulting from transition of solar-wind-driven vertical flow to velocities approaching Mach 1.

Cloutier, P. A.↗
NASA NTRS1989

Probabilistic modeling of solar power systems

The author presents a probabilistic approach based on Markov chain theory to model stand-alone photovoltaic power systems and predict their long-term service performance. The major advantage of this approach is that it allows designers and developers of these systems to analyze the system performance as well as the battery subsystem performance in the long run and determine the system design requirements that meet a specified service performance level. The methodology presented is illustrated by using data for a radio repeater system for the Boston, Massachusetts, location.

Safie, Fayssal M.↗
NASA NTRS1988

Insensitivity of solar p-mode frequencies to changes in the helium abundance

P-mode oscillation spectra (l = 0-4; n = 12-30) were calculated for three solar models with helium mass fractions Y = 0.230, 0.235, and 0.240. The solar models were tuned to have the Sun's radius and luminosity by adjusting both the age and the ratio of the mixing length to pressure scale height parameter. The models were identically constrained in all other respects. A 4 percent change in the mass fraction of helium produces less than a 0.1 percent change in the frequencies of the low degree p-modes. This result implies that it will be very difficult to determine the helium abundance of the sun directly from the p-mode oscillation spectrum since the frequencies of the modes are relatively insensitive to changes in the helium abundance.

Guenther, D. B.↗
NASA NTRS1977

Hydrostatic and dynamic models of solar coronal holes

A description is presented of a sequence of one-dimensional fluid flow models of the transition zone and the inner corona. A hydrostatic model atmosphere in reasonable agreement with observations of closed, large-scale coronal structures found in the quiet sun is considered and various physical effects are introduced, one at a time, observing the response of the model. As a result of the investigations, a model is developed of the plasma flow in a coronal hole. It is shown that the data severely circumscribe the allowable range of possible models.

Rosner, R.↗
NASA NTRS1986

A two-fluid solar wind model with Alfven waves - Parameter study and application to observations

The effects of Alfven waves from the inner corona on the solar wind density profile, flow velocity and on the random motion of protons are studied. Different base densities, temperatures, and wave velocity amplitudes, as well as different flow geometries, are considered. The model calculations are compared to simultaneous observations of the electron density profile and the resonantly scattered Lyman alpha line. Present observations, out to 4 solar radii, can be used to place limits on the coronal base density and temperature, and put an upper limit on the wave amplitude. It is pointed out that future observations of the electron density and the Lyman alpha line, out to larger heliocentric distances, and of lines from heavier elements, should be used to place more stringent constraints on the amplitudes of MHD waves in the corona.

Esser, R.↗
DOE OSTI2018

Computational analysis of metamaterial–aluminum–silicon solar cell model

In this paper, the optical parameters of an improved waveguide structure for a more efficient silicon solar cell are studied. Despite its favorable electronic, physical, and chemical properties, silicon remains a poor absorber of light. The optical losses due to the reflection at the air/glass interface of the cell and the transmission at its back are other factors, which limit the cell conversion efficiency. Consequently, several mechanisms for light trapping capable to increase the collection of the incident photons as electrical current and to decrease the transmission loss, have been developed. In this context, we propose a multilayer waveguide structure in which the sunlight is guided by a metamaterial layer and the transmission loss is eliminated by an aluminum back reflector. The reflection and transmission coefficients are derived by using the Generalized Transfer Matrix Method. The application of the law of conservation of energy allowed the determination of the absorption coefficient. These optical parameters are examined for several angles of incidence for s-polarized light, p-polarized light and unpolarized light. Simulation results show a significant reduction of reflection and a complete suppression of transmission.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗