Solution of the Three-Dimensional Navier-Stokes Equations for a Turbulent Horseshoe Vortex Flow PDF Download
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Author: R. C. Buggelin Publisher: ISBN: Category : Languages : en Pages : 36
Book Description
The problem of three dimensional turbulent horseshoe vortex/corner flow is investigated numerically. Solutions of the compressible Reynolds averaged Navier Stokes equations are computed using a linearized block implicit scheme with Douglas Gunn splitting. Solutions are computed using both two equation (k-epsilon) and algebraic mixing length turbulence models, with grid distributions which provide resolution of the viscous sublayer regions. These computed results are displayed graphically and compared with recent experimental measurements. There is good qualitative agreement between computed and measured mean flow velocities, especially near the saddle point separation line. The computed corner flow has a multiple vortex structure. There are quantitative differences in details of the weak corner flows downstream of the leading edge, which may be attributable to the turbulence model used and/or numerical error. Convergence required approximately 150 iterations using a 60x50x40 grid (120,000 points) and required about 2.5 hours of CRAY-XMP run time. Keywords: Three Dimensional Flow; Navier Stokes Equations; Turbulent Flow; Horseshoe Vortex Flow; Implicit Algorithm.
Author: R. C. Buggelin Publisher: ISBN: Category : Languages : en Pages : 36
Book Description
The problem of three dimensional turbulent horseshoe vortex/corner flow is investigated numerically. Solutions of the compressible Reynolds averaged Navier Stokes equations are computed using a linearized block implicit scheme with Douglas Gunn splitting. Solutions are computed using both two equation (k-epsilon) and algebraic mixing length turbulence models, with grid distributions which provide resolution of the viscous sublayer regions. These computed results are displayed graphically and compared with recent experimental measurements. There is good qualitative agreement between computed and measured mean flow velocities, especially near the saddle point separation line. The computed corner flow has a multiple vortex structure. There are quantitative differences in details of the weak corner flows downstream of the leading edge, which may be attributable to the turbulence model used and/or numerical error. Convergence required approximately 150 iterations using a 60x50x40 grid (120,000 points) and required about 2.5 hours of CRAY-XMP run time. Keywords: Three Dimensional Flow; Navier Stokes Equations; Turbulent Flow; Horseshoe Vortex Flow; Implicit Algorithm.
Author: W. R. Briley Publisher: ISBN: Category : Languages : en Pages : 43
Book Description
A low Mach number formulation of the three-dimensional Navier-Stokes equations is solved for a steady laminar horseshoe vortex flow, using a time-iterative approach. A split linearized block implicit algorithm is used, with central spatial differences in a transformed coordinate system. The stability of this algorithm in three dimensions is examined for a scalar convection model problem, and results are obtained which suggest that the algorithm is both conditionally stable and rapidly convergent when nonperiodic inflow/outflow boundary conditions are used. A new form of artificial dissipation which acts along physical streamlines instead of coordinate grid lines is also tested and found to introduce less error when the local flow direction is not aligned with the computational grid. An accurate solution for a laminar horseshoe vortex flow is computed using an improved solution algorithm with small artificial dissipation. This solution does not change significantly when the mesh spacing is halved using (15 x 15 x 15) and (29 x 29 x 29) grids. Very good convergence rates were obtained, such that residuals were reduced by a factor of 1/100 in 30 and 60 iterations respectively, for 3,375 and 24,389 grid points. (Author).
Author: W. Roger Briley Publisher: ISBN: Category : Languages : en Pages : 9
Book Description
Numerical solutions of the compressible Navier-Stokes equations are presented for a laminar horseshoe vortex flow created by the interaction of a boundary layer on a flat surface and an elliptical strut leading edge mounted normal to the flat surface. The computational approach utilizes zone embedding, surface-oriented elliptic-cylindrical coordinates, interactive boundary conditions, and a consistently-split linearized block implicit (LBI) scheme developed by the authors. Mesh resolution tests are performed, and the horseshoe vortex flow is discussed. (Author).
Author: W. R. Briley Publisher: ISBN: Category : Languages : en Pages : 55
Book Description
Three-dimensional turbulent horseshoe vortex flow past strut/endwall configurations having both unswept and 45-degree swept leading edges is studied by numerical solution of the compressible Reynolds-averaged Navier-Stokes equations. The Cartesian form of the equations is transformed to a general nonorthogonal coordinate system which is fitted to the geometry of interest and then solved using a consistently-split linearized block implicit (LBI) algorithm. The turbulence model and computational mesh provides for resolution of the viscous sublayer and employs an isotropic eddy viscosity based on solution of the turbulence kinetic energy equation and a specified length scale. Although no flow measurements are available for the region near the leading edge, predictions of the horseshoe vortex formation near the leading edge are in qualitative agreement with flow visualization studies of similar flows. Predictions of the relatively weak secondary flow in the corner region well downstream of the unswept leading edge do not agree with available measurements, and this is believed to be the result of numerical truncation error and/or inadequacy of the turbulence model. (Author).