Engineering topics
Publications and source records attributed to Sheaffer, Y. S..
A finite difference machine code is used in the wake vortex problems in the quasi-cylindrical boundary layer approximation. A turbulent energy model containing new features is developed that accounts for the major effects disclosed by more advanced models in which the parameters are not yet established. Several puzzles that arose in previous theoretical investigations of wake vortices are resolved.
Methods for reduction of velocities in trailing vortices of large aircraft are of current interest for the purpose of shortening the waiting time between landings at central airports. We have made finite-difference calculations of the flow in turbulent wake vortices as an aid to interpretation of wind-tunnel and flight experiments directed toward that end. Finite-difference solutions are capable of adding flexibility to such investigations if they are based on an adequate model of turbulence. Interesting developments have been taking place in the knowledge of turbulence that may lead to a complete theory in the future. In the meantime, approximate methods that yield reasonable agreement with experiment are appropriate. The simplified turbulence model we have selected contains features that account for the major effects disclosed by more sophisticated models in which the parameters are not yet established. Several puzzles are thereby resolved that arose in previous theoretical investigations of wake vortices.
A finite-difference machine code is brought to bear on the wake-vortex problem in the quasi-cylindrical boundary-layer approxmation. A turbulent-energy model containing new features is developed that accounts for the major effects disclosed by more advanced models in which the parameters are not yet established. Several puzzles are resolved that arose in previous theoretical investigations of wake vortices.
A finite-difference machine code is brought to bear on the wake-vortex problem in the quasi-cylindrical boundary-layer approximation. A turbulent-energy model containing new features is developed. Parameters of the model are evaluated by comparison of calculated velocities and turbulent intensities with measurements in an axisymmetric wake. Comparisons are made with a previous calculation of the decay of an isolated vortex and with wind tunnel and flight measurements in trailing vortices. A self-similar solution develops at large axial distance that decays with the square root of distance. A slower decay occurs in the preceding transition region.
A simple eddy-viscosity model is shown to make it possible to calculate numerically the mean properties of a turbulent wake. Although the structure of the Reynolds stress terms is not resolved, the results obtained are adequate for predicting velocity profiles and displacement thicknesses.
Solving nonsimilar laminar boundary layer equations including foreign gas injection
Diffusive transport term in hydrodynamic equations describing flow over strongly ablating entry objects, discussing charge separation and pressure diffusion
Hydrodynamics of plasma flow in pericapillary spaces, postulating fluid annulus outside capillary wall as plasma reservoir responsible for hematocrit ratios
Radiative flux and flux divergence for hot gas, considering spectral frequency, gas volume and spectral variation
Hydrodynamic analysis of dynamic blood plasma flow in capillaries and lymph annulus
Nonequilibrium flow field behind normal shock waves in carbon dioxide