Abstract

The Cartesian cut-cell method is one of the most promising methods for computational fluid dynamics due to its sharp interface treatment. However, the Cartesian cut-cell method and other Cartesian mesh solvers have difficulty with concentrating grid to boundary layers. The wall-modelling of shear stress is one of the most effective methods to reduce computational grids in boundary layers. This study investigated the applicability of a wall-stress model to the Cartesian cut-cell method. In the numerical simulations of the flow around a triangular column, Cartesian cut-cell simulation with the wall-stress model adequately predicted the drag coefficient. In the numerical simulations of the flow around a 30P30N high-lift airfoil configuration, the Cartesian cut-cell simulation with the wall-stress model adequately predicts the lift coefficient. The intermittent vortex structure of the outer layer of the turbulent boundary layer was observed on the suction side of the main element and the flap. The Cartesian cut-cell method with a wall-stress model is useful for predicting high Reynolds number flows at R e ∼ 10 6 .

Highlights

  • High Reynolds number flows Re & 106 frequently appear in the aerodynamic design of aircrafts and spacecrafts

  • The intermittent vortex structure of the outer layer of the turbulent boundary layer was observed on the suction side of the main element and the flap

  • Flow separation occurs at the downstream-side sharp edges, and a complex vortex structure that contains longitudinal vortices is formed in the wake

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Summary

Introduction

High Reynolds number flows Re & 106 frequently appear in the aerodynamic design of aircrafts and spacecrafts. The interaction between the object and the fluid is given by wall flux vectors across the cut plane Due to this sharp interface treatment and the robust grid generation of the Cartesian mesh, the Cartesian cut-cell method is one of the most promising methods in CFD. The Cartesian cut-cell method and other Cartesian mesh solvers [14,15,16] struggle to satisfy the required grid resolution for boundary layers because rectangular cells with an extremely large aspect ratio used in boundary fitted mesh are not available with these methods To overcome this difficulty, an appropriate near-wall treatment is required. The numerical results of the present study revealed the prediction capability of the wall-stress model to the Cartesian cut-cell simulation of unsteady flows

Governing Equation
Wall-Stress Model
Flow around a Triangular Column
Simulation Conditions
Simulation Results
Flow around the 30P30N Three-Element High-Lift Airfoil Configuration
Simulation Result by Wall-Modelled Navier–Stokes Simulation
Simulation Result with the Euler Equation
Conclusions

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