Yoshiharu Tamaki

An improved immersed boundary method for turbulent flow simulation on Cartesian grids is proposed. To determine the appropriate boundary conditions, near-wall approximation of the mean-flow equation and the Spalart–Allmaras turbulence model is investigated. A modified near-wall velocity profile that is linear with respect to the distance from the wall and that can be resolved by a numerical scheme with second-order spatial accuracy is derived. As with the velocity profile, the eddy-viscosity pro

Transonic turbulent flows around the NASA Common Research Model are simulated to investigate the capability of the Cartesian-grid-based flow solver UTCart in three-dimensional high-Reynolds-number flow simulations. UTCart consists of an automatic Cartesian grid generator based on an octree structure and a compressible flow solver that uses an immersed boundary method with a turbulent wall function for the wall boundary condition. Using the UTCart grid generator, the medium grid (approximately 50

Predictability of trailing-edge stall phenomena using wall-modeled large-eddy simulations (LES) is investigated with a wall-resolved LES database. An analysis based on the momentum integral relation shows that the skin friction accumulation effect near the leading edge to the mid chord dominates boundary layer development, and thus, affects flow separation prediction near the trailing edge. The results indicate that accurate wall modeling near the leading edge to the mid chord is essential for p

In this paper a novel methodology is proposed for wall-modeled large eddy simulation (WMLES) on non-body-conforming Cartesian grids. The proposed WMLES employs a partial-slip velocity boundary condition to reduce conservation errors at the wall. In addition, since the slip velocity reduces the shear stress in the near-wall region, a modeled turbulence shear stress is introduced to maintain the shear-stress balance in the near-wall region. The proposed WMLES robustly predicts turbulence statistic

A wall-resolved large-eddy simulation (LES) of the near-stall flow around the Aerospatiale A-airfoil at [Formula: see text] is conducted. The present LES shows typical Reynolds-number effects compared to the previous LES at [Formula: see text], such as the increase in lift coefficient, decrease in boundary-layer thickness, delay of turbulent flow separation, and upstream shift of transition location. Among these Reynolds-number effects, the difference in the development of momentum displacement

The secondary motion caused by turbulence anisotropy is one of the crucial factors for determining the size of corner-flow separation in a side-wall interference flow field. Therefore, through a wall-resolved large-eddy simulation (LES) of a side-wall interference flow field, this study investigates the effects of the secondary motion on the corner-flow separation and explores the turbulence modelling that can reproduce the secondary flow motion. The momentum transport analysis using the LES res

This study investigates the capability of wall-modeled large-eddy simulation (WMLES) in predicting the transonic buffet phenomenon over three-dimensional aircraft configurations at high Reynolds numbers. The WMLES is conducted using the Cartesian-grid-based flow solver FrontFlow/Violet Hierarchical Cartesian for Aeronautics Based on Compressible-Flow Equations (FFVHC-ACE). To extend the capability of FFVHC-ACE to transonic flow simulations with shock waves, a hybrid kinetic energy and entropy pr

View Video Presentation: https://doi.org/10.2514/6.2023-0429.vid This study demonstrates the capability of the wall-modeled large-eddy simulation for predicting buffet phenomena over a 3D aircraft configuration. For the WMLES around complex 3D geometries, the Cartesian-grid-based flow solver FrontFlow/Violet Hierarchical Cartesian for Aeronautics based on Compressible-flow Equations (FFVHC-ACE) is employed. To extend the applicability of FFVHC-ACE to transonic flow simulations, the authors devel

View Video Presentation: https://doi.org/10.2514/6.2022-3435.vid Wall-modeled large-eddy simulations (WMLES) around the NASA High-lift Common Research Model (CRM-HL) are conducted by the fully-automated Cartesian-grid-based flow solver FFVHC-ACE for the fourth AIAA CFD High Lift Prediction Workshop. To realize highly accurate WMLES, FFVHC-ACE employs the wall modeling for non-body-conforming grids and the KEEP scheme. The computational grids contain 11.1B grid points at maximum, and the computat