The Experts below are selected from a list of 94425 Experts worldwide ranked by ideXlab platform

Anders Wörman - One of the best experts on this subject based on the ideXlab platform.

Susa H. Stone - One of the best experts on this subject based on the ideXlab platform.

David A. Kopriva - One of the best experts on this subject based on the ideXlab platform.

  • Spectral Solution of the viscous blunt-body problem 2 - Multidomain approximation
    AIAA Journal, 1996
    Co-Authors: David A. Kopriva
    Abstract:

    We present steady Solutions of high-speed viscous flows over blunt bodies using a multidomain Chebyshev Spectral collocation method. The region within the shock layer is divided into subdomains so that internal layers can be well resolved. In the interiors of the subdomains, the Solution is approximated by Chebyshev collocation. At interfaces between subdomains, the advective terms are upwinded and the viscous terms are treated by a penalty method. The method is applied to five flows in the Mach number range 5-25 and Reynolds number range from 2 x 10 3 to 83 x 10 4 , based on nose radius. Results are compared with experimental data and to a finite difference Solution.

  • Multidomain Spectral Solution of compressible viscous flows
    Journal of Computational Physics, 1994
    Co-Authors: David A. Kopriva
    Abstract:

    Abstract We develop a nonoverlapping multidomain Spectral collocation method to solve compressible viscous flows. At the interfaces, the advection terms are treated with a characteristic correction method. The diffusion terms are treated with a penalty method. Spectral accuracy is demonstrated on linear model problems in one and two space dimensions. The method is applied to a subsonic and a supersonic flow over a flat plate. The results are compared to Solutions of the boundary-layer equations which show that two digit accuracy in the adiabatic plate temperature is obtained with 16 points in the boundary layer for a freestream Mach number of two. A second application is to a transonic flow in a two-dimensional converging-diverging nozzle, where the computed results are compared to experimental data.

  • Spectral Solution of the viscous blunt-body problem
    AIAA Journal, 1993
    Co-Authors: David A. Kopriva
    Abstract:

    The viscous blunt-body problem is solved with a shock-fitted Chebyshev Spectral method. No explicit artificial viscosity or filtering is needed to obtain smooth, converged Solutions. The method is applied to two problems. First, results for the flow over a right circular cylinder in the Mach number range of 5.5-6.0 are compared with experimental data. Second, a Solution for a Mach 25 flow over a hyperbolic cone is compared with a viscous shock-layer calculation.

  • Spectral Solution of inviscid supersonic flows over wedges and axisymmetric cones
    Computers & Fluids, 1992
    Co-Authors: David A. Kopriva
    Abstract:

    Abstract We use a shock-fitted multidomain Spectral collocation method to solve both steady and unsteady inviscid supersonic flows over bodies. New aspects of the method include two subdomain interface types and a zonal Solution procedure to get efficient convergence to steady-state in supersonic regions. Steady-state examples include flow over a sharp cone, a hyperbolic cone and a hyperbolic wedge. For the cone, the exact flow Solution is used to show that the method is Spectrally accurate. As an example of an unsteady flow, we present a calculation of the interaction of a free-stream hot ring with the flow over a sharp cone.

  • Multidomain Spectral Solution of the Euler Gas-dynamics equations
    Journal of Computational Physics, 1991
    Co-Authors: David A. Kopriva
    Abstract:

    Abstract We present interface treatments for computing the Euler gas-dynamics equations by a multidomain Chebyshev Spectral collocation method. These treatments are suitable for use at the corners of subdomains and for patched or overlapping subdomains. They can be applied to interfaces placed in subsonic, supersonic, or transonic regions of a flow. Computed results indicate that the Solutions are Spectrally accurate, can be more accurate and more efficient than a single domain calculation, and that reflections of waves at interfaces are not significant.

Lars Marklund - One of the best experts on this subject based on the ideXlab platform.

  • The use of Spectral analysis-based exact Solutions to characterize topography-controlled groundwater flow
    Hydrogeology Journal, 2011
    Co-Authors: Lars Marklund, Anders Wörman
    Abstract:

    Spectral analysis enhances the ability to analyze groundwater flow at a steady state by separating the top boundary condition into its periodic forms. Specifically, Spectral analysis enables comparisons of the impact of individual spatial scales on the total flow field. New exact Spectral Solutions are presented for analyzing 3D groundwater flow with an arbitrarily shaped top boundary. These Solutions account for depth-decaying, anisotropic and layered permeability while utilizing groundwater flux or the phreatic surface as a top boundary condition. Under certain conditions, groundwater flow is controlled by topography. In areas where the groundwater flow is controlled by the topography, the unknown water table is often approximated by the topography. This approximation induces a systematic error. Here, the optimal reSolution of digital elevation models (DEMs) is assessed for use as a top boundary in groundwater flow models. According to the analysis, the water-table undulation is smoother than the topography; therefore, there is an upper limit to the reSolution of DEMs that should be used to represent the groundwater surface. The ability to represent DEMs of various Spectral Solutions was compared and the results indicate that the fit is strongly dependent on the number of harmonics in the Spectral Solution.

  • exact three dimensional Spectral Solution to surface groundwater interactions with arbitrary surface topography
    Geophysical Research Letters, 2006
    Co-Authors: Anders Wörman, Aaron I. Packman, Lars Marklund, Judson W. Harvey, Susa H. Stone
    Abstract:

    It has been long known that land surface topography governs both groundwater flow patterns at the regional-to-continental scale and on smaller scales such as in the hyporheic zone of streams. Her ...

  • Exact three‐dimensional Spectral Solution to surface‐groundwater interactions with arbitrary surface topography
    Geophysical Research Letters, 2006
    Co-Authors: Anders Wörman, Aaron I. Packman, Lars Marklund, Judson W. Harvey, Susa H. Stone
    Abstract:

    It has been long known that land surface topography governs both groundwater flow patterns at the regional-to-continental scale and on smaller scales such as in the hyporheic zone of streams. Her ...

Aaron I. Packman - One of the best experts on this subject based on the ideXlab platform.