Physics: Posters

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Browsing Physics: Posters by Author "Craft, Kyle"

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    A Test of the Validity of Inviscid Wall-Modeled LES
    (Houghton College, 2015-11-22) Redman, Andrew; Craft, Kyle; Aikens, Kurt
    Computational expense is one of the main deterrents to more widespread use of large eddy simulations (LES). As such, it is important to reduce computational costs whenever possible. In this vein, it may be reasonable to assume that high Reynolds numbers flows with turbulent boundary layers and inviscid when using a wall model. This assumption relies on the grid being too coarse to resolve either the viscous length scales in the outer flow or those near near walls. We are not aware of other studies that have suggested or examined the validity of this approach. The inviscid wall-modeled LES assumption is tested here for supersonic flow over a flat plate on three differennt grids. Inviscid and viscous results are compared to those of another wall-modelled LES as well as experimental data-the results appear promising. Furthermore, the inviscid assumption reduces simulation costs by about 25% and 39% for supersonic and subsonic flows, respectively, with the current LES aapplication. Reccommendations are presented as are future areas of research.
    68th Annual Meeting of the APS Division of Fluid Dynamics, Boston, MA, Nov. 22-24, 2015; XXXV Annual Rochester Symposium for Physics Students, University of Rochester, Rochester, NY., April 2, 2016.
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    Progress Towards an LES Wall Model Including Unresolved Roughness
    (Houghton College, 2015-11-22) Craft, Kyle; Redman, Andrew; Aikens, Kurt
    Wall models used in large eddy simulations(LES) are often based on the oriesforhy draulically smooth walls. While this is reasonable for many applications, there are also many where the impact of surface roughness is important. A previously developed wall model has been used primarily for jet engine aeroacoustics. However, jet simulations have not accurately captured thick initial shear layers found in some experimental data. This may partly be due to nozzle wall roughness used in the experiments to promote turbulent boundary layers. As a result, the wall model is extended to include the effects of unresolved wall roughness through appropriate alterations to the log-law. The methodology is tested for incompressible flat plate boundary layers with different surface roughness. Correct trends are noted for the impact of surface roughness on the velocity profile. However, velocity deficit profiles and the Reynolds stresses do not collapse as well as expected for higher roughness. Possible reasons for the discrepancies as well as future work are presented.
    68th Annual Meeting of the APS Division of Fluid Dynamics, Boston, MA, Nov. 22-24, 2015; XXXV Annual Rochester Symposium for Physics Students, University of Rochester, Rochester, NY., April 2, 2016.