High Reynolds Number Airfoil Simulations Using the Immersed Boundary Method

2012 ◽  
Author(s):  
James P. Johnson ◽  
Gianluca Iaccarino ◽  
Kuo-Huey Chen ◽  
Bahram Khalighi
Keyword(s):  
Immersed Boundary Method ◽  
High Reynolds Number ◽  
Aerodynamic Force ◽  
Reynolds Numbers ◽  
Computational Approach ◽  
Immersed Boundary ◽  
Pressure Distributions ◽  
Boundary Method ◽  
High Reynolds ◽  
Naca 0012

The Immersed-Boundary Method is coupled to an incompressible-flow RANS solver, based on a two-equation turbulence model, to perform unsteady numerical simulations of airflow past the NACA-0012 airfoil for several angles of attack and Reynolds numbers of 5.0×105 and 1.8×106. Qualitative characterizations of the flow in the vicinity of the airfoil are obtained to show the need for locally refined grids to capture the thin boundary layers close to the airfoil leading edges. Quantitative analysis of aerodynamic force coefficients and wall pressure distributions are also reported and compared to experimental results and those from body-fitted grid simulations using the same solver to assess the accuracy and limitations of this approach. The Immersed-Boundary simulations compared well to the experimental and body-fitted results up to the occurrence of separation. After that point, neither computational approach provided satisfactory solutions.

Simulations of High Reynolds Number Air Flow Over the NACA-0012 Airfoil Using the Immersed Boundary Method

2014 ◽  
Vol 136 (4) ◽  
Author(s):  
James P. Johnson ◽  
Gianluca Iaccarino ◽  
Kuo-Huey Chen ◽  
Bahram Khalighi
Keyword(s):  
Immersed Boundary Method ◽  
Aerodynamic Force ◽  
Leading Edge ◽  
Wake Flow ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Boundary Method ◽  
Computational Mesh ◽  
High Reynolds ◽  
Naca 0012

The immersed-boundary method is coupled to an incompressible-flow Reynolds-averaged Navier Stokes solver, based on a two-equation turbulence model, to perform unsteady numerical simulations of airflow past the NACA-0012 airfoil for several angles of attack and Reynolds numbers of 5.0×105 and 1.8×106. A preliminary study is performed to evaluate the sensitivity of the calculations to the computational mesh and to guide the creation of the computational cells for the unsteady calculations. Qualitative characterizations of the flow in the vicinity of the airfoil are obtained to assess the capability of locally refined grids to capture the thin boundary layers close to the airfoil leading edge as well as the wake flow emanating from the trailing edge. Quantitative analysis of aerodynamic force coefficients and wall pressure distributions are also reported and compared to experimental results and those from body-fitted grid simulations using the same solver to assess the accuracy and limitations of this approach. The immersed-boundary simulations compared well to the experimental and body-fitted results up to the occurrence of separation. After that point, neither computational approach provided satisfactory solutions.

A discrete-forcing immersed boundary method for turbulent-flow simulations

2020 ◽  
pp. 147509022092724 ◽  
Author(s):  
Haixuan Ye ◽  
Yang Chen ◽  
Kevin Maki
Keyword(s):  
Reynolds Number ◽  
Turbulent Flows ◽  
Immersed Boundary Method ◽  
High Reynolds Number ◽  
Immersed Boundary ◽  
High Quality ◽  
Boundary Method ◽  
High Reynolds ◽  
Reynolds Number Flows ◽  
Near Wall

For numerical simulations of ship hydrodynamics in high Reynolds number, near-wall grids with high quality are essential to accurately predict the flow field and shear stress. This article proposes a discrete-forcing immersed boundary method to simulate moving solid boundaries in turbulent flows. The technique will efficiently remove the requirement of high-quality body-conforming grids and also preserve the grid quality throughout the simulation when body motions are considered. The one-equation Spalart–Allmaras turbulence model is coupled with the immersed boundary method for turbulence closure. A key aspect of this method is to use a wall function to alleviate the near-wall cell-size requirement in high-Reynolds-number flows. In this method, the boundary conditions on the immersed surfaces are enforced without the need of spreading functions, which is favorable for high-Reynolds-number flows. The performance of the method is carefully verified and validated through various problems, including both laminar and turbulent flows for fixed and moving solid surfaces. Subsequently, this method is further examined by predicting the turbulent flows around a model-scaled double-body KVLCC2 tanker. The total resistance and the local wake field are compared with experimental data.

COMPUTATIONAL SIMULATION OF FLUID FLOW OVER A TRIANGULAR STEP USING IMMERSED BOUNDARY METHOD

2013 ◽  
Vol 10 (04) ◽  
pp. 1350016 ◽  
Author(s):  
C. A. SALEEL ◽  
A. SHAIJA ◽  
S. JAYARAJ
Keyword(s):  
Fluid Flow ◽  
Immersed Boundary Method ◽  
Reynolds Numbers ◽  
Stream Line ◽  
Immersed Boundary ◽  
Complex Geometries ◽  
Backward Facing Step ◽  
Fractional Step Method ◽  
Boundary Method ◽  
Fluid Solid Interaction

Handling of complex geometries with fluid–solid interaction has been one of the exigent issues in computational fluid dynamics (CFD) because most engineering problems have complex geometries with fluid–solid interaction for the purpose. Two different approaches have been developed for the same hitherto: (i) The unstructured grid method and (ii) the immersed boundary method (IBM). This paper details the IBM for the numerical investigation of two-dimensional laminar flow over a backward facing step and various geometrically configured triangular steps in hydro-dynamically developing regions (entrance region) as well in the hydro-dynamically developed regions through a channel at different Reynolds numbers. The present numerical method is rooted in a finite volume approach on a staggered grid in concert with a fractional step method. Geometrical obstructions are treated as an immersed boundary (IB), both momentum forcing and mass source terms are applied on the obstruction to satisfy the no-slip boundary condition and also to satisfy the continuity for the mesh containing the immersed boundary. Initially, numerically obtained velocity profiles and stream line plots for fluid flow over backward facing step is depicted to show its excellent agreement with the published results in various literatures. There after profiles and plots in the channel with triangular steps are also being unveiled with in depth elucidation. Results are presented for different Reynolds numbers.

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