Bulletin of the American Physical Society
71st Annual Meeting of the APS Division of Fluid Dynamics
Volume 63, Number 13
Sunday–Tuesday, November 18–20, 2018; Atlanta, Georgia
Session E38: Large Eddy Simulations: Wall Modeling |
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Chair: J. A. Domaradzki, University of Southern California Room: Georgia World Congress Center Ballroom 1/2 |
Sunday, November 18, 2018 5:10PM - 5:23PM |
E38.00001: Large eddy simulation of transitional boundary layer flow with two-parameter mixed models Young Mo Lee, Hyeon Gyu Hwang, Jae Hwa Lee Large eddy simulation of a transitional boundary layer flow is performed to assess modified two-parameter mixed models. Because energy transfer between the grid-scale and subgrid-scale has to be modeled to characterize a transitional boundary layer flow, we combine the scale-similarity model and eddy viscosity model as a mixed model. For the proposed mixed models, the two model coefficients are determined by dynamic procedures and the effects of a stress tensor that involves the interaction between the resolved and unresolved scales are considered to estimate the proper energy exchange between large-scales and subgrid-scales. The proposed mixed model with the dynamic Smagorinsky model shows improved prediction in the skin-friction coefficient and shape factor in a transition region, compared to the earlier studies with various subgrid-scale models. The energy dissipation predicted by the present mixed model shows a good agreement with a filtered direct numerical simulation data, although the magnitude of the modeled dissipation is slightly underestimated. |
Sunday, November 18, 2018 5:23PM - 5:36PM |
E38.00002: Dynamic slip wall model for large-eddy simulation Hyunji Jane Bae, Adrian Lozano-Duran, Sanjeeb T Bose, Parviz Moin Wall models are necessary to overcome the limitation of subgrid scale models in the near-wall region. The use of the slip boundary condition with transpiration for wall-modeled large-eddy simulation is motivated by theoretic assessment and a priori testing using direct numerical simulation (DNS) data. A dynamic slip wall model based on the invariance of wall stress under test filtering is proposed. The dynamic wall-stress-invariant model is free of any a priori specified coefficients, unlike traditional wall models which are based on RANS models. The performance of the model is tested for channel flows up to Reτ = 8000, and spatially evolving boundary layers up to Reθ = 10,000 for various grid resolutions. Predictions of the mean velocity profile and turbulence intensities are in good agreement with DNS and experimental data.
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Sunday, November 18, 2018 5:36PM - 5:49PM |
E38.00003: Surrogate wall modeling for large-eddy simulations with diffuse-interface immersed boundary method Guowei He, Shizhao Wang, Beiji Shi The diffuse-interface immersed boundary method has rarely been used in the large-eddy simulation of wall-bounded turbulent flows despite its efficiency and robustness in handling walls. The primary shortcomings of the method are the unavailability of explicit reconstructions of velocities and the low fidelity of interpolations contaminated by the diffuse-interface. We propose a surrogate wall model to circumvent these shortcomings. Its main features are (1) to construct a Lagrangian surrogate layer near the wall to introduce explicit reconstructions of velocities, (2) to reconstruct the velocities at the surrogate layer using a near wall model, and (3) impose the immersed boundary method on the surrogate layer instead of the wall to reduce the undesirable effects of the diffuse-interface on flows. The surrogate wall model is used to simulate the canonical plane channel flows at different Reynolds numbers and further tested against flows over periodic hills. The results obtained are in agreement with those of boundary-conformal mesh and/or sharp-interface immersed boundary method. |
Sunday, November 18, 2018 5:49PM - 6:02PM |
E38.00004: A Predictive Near-Wall Model for Large Eddy Simulations Prakash Mohan, Robert D Moser Large eddy simulations directly represent larger scale turbulent motions and model the effects of small scale motions. However in the near-wall region the large, dynamically important eddies are on the order of viscous scales, which makes resolving them very expensive. It is therefore desirable to formulate an approach where the near-wall region is modeled, leading to the so-called wall-modeled LES. |
Sunday, November 18, 2018 6:02PM - 6:15PM |
E38.00005: Wall-modeled LES using the anisotropy resolving one-equation SGS model Kazuhiko Suga, Tomoki Sakamoto, Yusuke Kuwata The idea of the analytical wall function (AWF) for RANS is applied to the SGS eddy viscosity inside the wall-adjacent-cells (wall-cells). With a modeled profile of the eddy-viscosity in the relatively coarse wall-cells, this wall model (SGS-AWF) integrates the thin-layer approximated momentum equation that includes the temporal, convection, and pressure gradient terms, to give the wall shear stress as the wall boundary condition of the momentum equation. The model coefficient of the SGS-AWF depends dynamically on the ratio of the SGS and GS time-scales. Coupled with the anisotropy resolving one-equation SGS model proposed by Abe (2013), the SGS-AWF is confirmed to perform better than the traditional wall-modeled LES in a separating and reattaching flow. |
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