High Reynolds Number Steady State Flow Simulation using Immersed Boundary Method

2014 ◽  
Author(s):  
Yuichi Takahashi ◽  
Taro Imamura
Keyword(s):  
Reynolds Number ◽  
Steady State ◽  
Immersed Boundary Method ◽  
High Reynolds Number ◽  
Flow Simulation ◽  
Immersed Boundary ◽  
Steady State Flow ◽  
State Flow ◽  
Boundary Method ◽  
High Reynolds

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.

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.

Time-Dependent Laminar Backward-Facing Step Flow in a Two-Dimensional Duct

1988 ◽  
Vol 110 (3) ◽  
pp. 289-296 ◽  
Author(s):  
F. Durst ◽  
J. C. F. Pereira
Keyword(s):  
Reynolds Number ◽  
Steady State ◽  
Separated Flow ◽  
Flow Region ◽  
Reynolds Numbers ◽  
Steady State Flow ◽  
Backward Facing Step ◽  
Step Flow ◽  
Recirculating Flow ◽  
State Flow

This paper presents results of numerical studies of the impulsively starting backward-facing step flow with the step being mounted in a plane, two-dimensional duct. Results are presented for Reynolds numbers of Re = 10; 368 and 648 and for the last two Reynolds numbers comparisons are given between experimental and numerical results obtained for the final steady state flow conditions. In the computational scheme, the convective terms in the momentum equations are approximated by a 13-point quadratic upstream weighted finite-difference scheme and a fully implicit first order forward differencing scheme is used to discretize the temporal derivatives. The computations show that for the higher Reynolds numbers, the flow starts to separate on the lower and upper corners of the step yielding two disconnected recirculating flow regions for some time after the flow has been impulsively started. As time progresses, these two separated flow regions connect up and a single recirculating flow region emerges. This separated flow region stays attached to the step, grows in size and approaches, for the time t → ∞, the dimensions measured and predicted for the separation region for steady laminar backward-facing flow. For the Reynolds number Re = 10 the separation starts at the bottom of the backward-facing step and the separation region enlarges with time until the steady state flow pattern is reached. At the channel wall opposite to the step and for Reynolds number Re = 368, a separated flow region is observed and it is shown to occur for some finite time period of the developing, impulsively started backward-facing step flow. Its dimensions change with time and reduce to zero before the steady state flow pattern is reached. For the higher Reynolds number Re = 648, the secondary separated flow region opposite to the wall is also present and it is shown to remain present for t → ∞. Two kinds of the inlet conditions were considered; the inlet mean flow was assumed to be constant in a first study and was assumed to increase with time in a second one. The predicted flow field for t → ∞ turned out to be identical for both cases. They were also identical to the flow field predicted for steady, backward-facing step flow using the same numerical grid as for the time-dependent predictions.

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