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The purpose of this work was to present current work and results of the Langley Aeronautics Directorate covering the areas of computational fluid dynamics, viscous flows, airfoil aerodynamics, propulsion integration, test techniques, and low-speed, high-speed, and transonic aerodynamics. The following sessions are included in this volume: theoretical aerodynamics, test techniques, fluid physics, and viscous drag reduction.
Turbulent flow of dilute viscoelastic non- Newtonian fluids in pipes, noting frictional characteristics, elastic fluid parameters, etc
A constitutive relation for an equivalent, homogeneous fluid is developed for the anisotropic viscous flow of an oriented assembly of discontinuous fibers suspended in a viscous fluid. The anisotropic viscous compliance matrix can be expressed in terms of three constants by assuming the equivalent fluid to be incompressible and the microstructure to have axial symmetry (transversely isotropic). By means of a micromechanics analysis, the three terms of the constitutive relation are expressed in terms of the viscosity of the matrix fluid, the fiber aspect ratio, and the fiber volume fraction. A comparison of the viscosity terms reveals that the elongational viscosity in the fiber direction varies as the square of the fiber aspect ratio and a complex function of the fiber volume fraction. Furthermore, the ratio of the axial elongational viscosity to the transverse elongational viscosity and both axial and transverse shear viscosities was shown to be 10 exp 4 - 10 exp 6 for fiber aspect ratio of 100-1000, except at extreme values of the fiber volume fraction.
Electron-acoustic, ion-acoustic and electromagnetic plane waves coupling at shock front in two fluid ionized viscous plasma
A method is described involving the measurement of the viscous desolidification (pour) point of wax-free lubricant fluids. This method is especially useful for pour point testing of experimental quantities, since only six to sixteen drops of the oil are required for a single determination (automatically performed in duplicate) with nearly full recovery of the sample. The technique consists of: (1) rapidly freezing a small, predetermined amount of the oil on the side of a small test tube to form a frozen drop of given dimensions; (2) immersing duplicates of the charged and stoppered tubes into a cold bath; and (3) measuring the temperature when the drop front has moved a predetermined distance as the bath warms up.
Flow stability down inclined plane for stratified fluid system consisting of two layers of viscous fluids of different densities
Design of fluid dynamically efficient ducts is addressed through the combination of an optimization analysis with a three-dimensional viscous fluid dynamic analysis code. For efficiency, a parabolic fluid dynamic analysis was used. Since each function evaluation in an optimization analysis is a full three-dimensional viscous flow analysis requiring 200,000 grid points, it is important to use both an efficient fluid dynamic analysis and an efficient optimization technique. Three optimization techniques are evaluated on a series of test functions. The Quasi-Newton (BFGS, eta = .9) technique was selected as the preferred technique. A series of basic duct design problems are performed. On a two-parameter optimization problem, the BFGS technique is demonstrated to require half as many function evaluations as a steepest descent technique.
A finite element solution algorithm is established for the two-dimensional Navier-Stokes equations governing the transient motion of a viscous incompressible fluid, i.e., hydrodynamics. Dependent variable transformation renders the differential equation description uniformly elliptic. The finite element algorithm is established using the Galerkin criterion on a local basis within the Method of Weighted Residuals. It is unconstrained with respect to system linearity, computational mesh uniformity or solution domain closure regularity. The finite element matrices are established using a linear 'natural coordinate function' description. Computational solutions using the COMOC computer program illustrate the various features of the algorithm including recirculating flows.
Photoviscuous technique for fluid flow studies - theory and experiments
In the setting of the conservation element-solution element (CE/SE) method, a new and unified wall boundary treatment for the Navier-Stokes and Euler Equations is proposed. In essence, the shear stress exerted on the fluid by a wall is modeled as a source term as a part of local spacetime flux conservation in the vicinity of a wall boundary. When the fluid is inviscid, the source term vanishes and the boundary condition reduces to the usual 'slip' condition. On the other hand, when the fluid is viscous, the source-term effect is consistent with the traditional no-slip condition. Numerical results show that the new treatment is robust, efficient, and accurate for viscous and inviscid flows.
Kinetic prediction theory for viscosity, thermal conductivity and diffusivity of binary liquid mixtures composed of molecules interacting with square-well potential
A numerical investigation of a viscous incompressible fluid with constant properties within a vortex sink rate sensor is undertaken. A computer program was developed, for obtaining the numerical solution of the Navier-Stokes equations, assuming laminar flow, having general prescribed inlet conditions and axisymmetric boundary conditions. Computational results for various viscous flows and assorted boundary conditions have been obtained. In the vortex chamber, the radial momentum is conserved, whereas the axial momentum is negligible. In the sink region, the radial and tangential velocities, as well as the tangential vorticities, have significantly high values. In the sink tube, the radial momentum is negligible. The radial momentum within the vortex chamber is converted to the axial momentum in the sink tube. A change in the flow rate had an appreciable effect within the sensor and particularly near the sink tube entrance. As the flow rate was increased, both the tangential velocity and tangential vorticity increased rapidly. At the higher flow rates, vortices were produced at the corner of the entrance section of the sink tube.
We revisit the theory of first-order quasilinear systems with diagonalizable principal part and only real eigenvalues, what is commonly referred to as strongly hyperbolic systems. We provide a self-contained and simple proof of local well-posedness, in the Hadamard sense, of the Cauchy problem. Our regularity assumptions are very minimal. As an application, we apply our results to systems of ideal and viscous relativistic fluids, where the theory of strongly hyperbolic equations has been systematically used to study several systems of physical interest.
A reexamination of some numerical methods is considered in light of the new class of computers which use vector streaming to achieve high computation rates. A study has been made of the effect on the relative efficiency of several numerical methods applied to a particular fluid flow problem when they are implemented on a vector computer. The method of Brailovskaya, the alternating direction implicit method, a fully implicit method, and a new method called partial implicitization have been applied to the problem of determining the steady state solution of the two-dimensional flow of a viscous imcompressible fluid in a square cavity driven by a sliding wall. Results are obtained for three mesh sizes and a comparison is made of the methods for serial computation.
A model of Io is presented that consists of an elastic inner core, a low strength asthenosphere, and a thin elastic outer shell. The middle layer is ssumed to posses negligible shear strength and to be characterized by a Newtonian viscosity. The fluid in the viscous layer is forced to circulate mainly by the tidal distortion in the outer shell, modeled here as a variation in the distortion amplitude. As a result, heat is generated in the fluid by viscous dissipation. There are three important unconstrained parameters in the model: the fluid viscosity, the thickness of the fluid layer, and the degree to which the distortion of the outer shell is affected by the fluid viscosity. For a wide range of these model parameters viscous heating can generate just as much or even more heat than does elastic dissipation is the outer shell. The model suggests that much of Io's heat flow may be generated below the outer shell and could provide a source of energy for any silicate volcanism on the satellite.
Dense, granular flows were examined to effectively capture and model bulk viscous properties in thin packed beds. A modified Couette cell with particle image velocimetry was used to experimentally determine pseudo-viscosity properties of four particulate media with varying morphologies: (1) iron oxide-coated SiO 2 particles, (2) CARBOBEAD CP30-60 particles, (3) CARBOBEAD CP40-100 particles, and (4) Al 2 O 3 beads. The pseudo-viscosity functions were fitted using a power law to correlate the measured shear stress as a function of measured shear rate. The pseudo-viscous functions were used as inputs to computation fluid dynamics models for a single-phase viscous fluid to predict granular flow profiles. Steady-state free surface velocity profiles at angular velocities <7 rad/s predicted by the model were in good agreement with the experimental particle image velocimetry measurements, resulting in Pearson correlation coefficients of 0.97 for iron-oxide coated SiO 2 particles and 0.95 for CP30-60 particles. As a result, this alternative approach to measuring pseudo-viscous properties under shearing and modeling bulk transport behavior of granular flow using computation fluid dynamics model offered significant reduction in computational load compared to discrete element methods.
Rotation, magnetic field and compressibility effects on disturbances due to slow oscillations of conducting sphere in viscous medium
Compilation and evaluation of diffusivity and viscosity data on gas and liquid turbulent flow systems