An Immersed Boundary Method for General Flow Applications

2010 ◽  
Author(s):  
Jack R. Edwards ◽  
Jung-IL Choi ◽  
Santanu Ghosh ◽  
Daniel A. Gieseking ◽  
Jeffrey D. Eischen
Keyword(s):  
Boundary Layer ◽  
Turbulent Flows ◽  
Immersed Boundary Method ◽  
Human Motion ◽  
Immersed Boundary ◽  
Computational Domain ◽  
General Flow ◽  
Boundary Method ◽  
Boundary Layer Interaction ◽  
A Cell

The development of a direct-forcing immersed-boundary method for general flow applications is outlined in this paper. A cell-classification procedure based on a signed distance to the nearest surface is used to separate the computational domain into cells outside the immersed object (‘field cells’), cells outside but adjacent to the immersed object (‘band cells’), and cells within the immersed object (‘interior cells’). Interpolation methods based on laminar / turbulent boundary layer theory are used to prescribe the flow properties within the ‘band cells’. The method utilizes a decomposition of the velocity field near embedded surfaces into normal and tangential components, with the latter handled using power-law interpolations to mimic the energizing effects of turbulent boundary layers. A procedure for directly embedding sequences of stereo-lithography files as immersed objects in the computational is described, as are extensions of the methodology to compressible, turbulent flows. Described applications include human motion, moving aerodynamic surfaces, and shock / boundary layer interaction flow control.

A Combined Volume of Fluid and Immersed Boundary Method for Modelling of Two-Phase Flows with High Density Ratio

2021 ◽  
Author(s):  
Qiu Jin ◽  
Dominic Hudson ◽  
W.G. Price
Keyword(s):  
Boundary Layer ◽  
Immersed Boundary Method ◽  
Density Ratio ◽  
Volume Of Fluid ◽  
High Density ◽  
Immersed Boundary ◽  
Two Phase Flows ◽  
Two Phase ◽  
Boundary Method ◽  
High Density Ratio

Abstract A combined volume of fluid and immersed boundary method is developed to simulate two-phase flows with high density ratio. The problems of discontinuity of density and momentum flux are known to be challenging in simulations. In order to overcome the numerical instabilities, an extra velocity field is designed to extend velocity of the heavier phase into the lighter phase and to enforce a new boundary condition near the interface, which is similar to non-slip boundary conditions in Fluid-Structure Interaction (FSI) problems. The interface is captured using a Volume of Fluid (VOF) method, and a new boundary layer is built on the lighter phase side by an immersed boundary method. The designed boundary layer helps to reduce the spurious velocity caused by the imbalance of dynamic pressure gradient and density gradient and to prevent tearing of the interface due to the tangential velocity across the interface. The influence of time step, density ratio, and spatial resolution is studied in detail for two set of cases, steady stratified flow and convection of a high-density droplet, where direct comparison is possible to potential flow analysis (i.e. infinite Reynold's number). An initial study for a droplet splashing on a thin liquid film demonstrates applicability of the new solver to real-life applications. Detailed comparisons should be performed in the future for finite Reynold's number cases to fully demonstrate the improvements in accuracy and stability of high-density ratio two-phase flow simulations offered by the new method.

scholarly journals CFD simulation of turbulent flows over wire-wrapped nuclear reactor bundles using immersed boundary method

2020 ◽  
Vol 1599 ◽  
pp. 012022
Author(s):  
Antonio Cervone ◽  
Andrea Chierici ◽  
Leonardo Chirco ◽  
Roberto Da Vià ◽  
Valentina Giovacchini ◽  
...  
Keyword(s):  
Turbulent Flows ◽  
Immersed Boundary Method ◽  
Nuclear Reactor ◽  
Cfd Simulation ◽  
Immersed Boundary ◽  
Boundary Method

Simulation Flows Over Hemisphere at the Bed of an Open Channel by DNS and Immersed Boundary Method

2003 ◽  
Author(s):  
T. X. Dinh
Keyword(s):  
Numerical Simulation ◽  
Turbulent Flows ◽  
Immersed Boundary Method ◽  
Open Channel ◽  
Three Dimensional ◽  
Turbulent Channel Flow ◽  
Time Dependent ◽  
Immersed Boundary ◽  
Boundary Method ◽  
Finite Different Method

The immediate aim of this study is to check the accuracy of Kajishima’s method (one kind of immersed boundary method) for the direct numerical simulation (DNS) of turbulent channel flow over a complicated bed. In this paper, the simulation of three dimensional, time -dependent turbulent flows over a fixed hemisphere at the bed of an open channel is carried out. A finite different method (FDM) is applied with a staggered Cartesian mesh. The forces, the moments about the center of the hemisphere, and the distribution of pressure on the hemisphere in the plane of symmetry are calculated.

Computation of Turbulent Flows in Complex and Moving Geometries Using Immersed Boundary Method

2003 ◽  
Author(s):  
Mayank Tyagi ◽  
Sumanta Acharya
Keyword(s):  
Turbulent Flows ◽  
Immersed Boundary Method ◽  
Complex Geometry ◽  
Fluid Motion ◽  
The Body ◽  
Immersed Boundary ◽  
Full Potential ◽  
Heated Cylinder ◽  
Boundary Method ◽  
Trapped Vortex

A solution methodology for complex turbulent flows of industrial interests is developed using Immersed Boundary Method (IBM). IBM combines the efficiency inherent in using a fixed Cartesian grid to compute the fluid motion, along with the ease of tracking the immersed boundary at a set of moving Lagrangian points. IBM relies upon the body force terms added in the momentum equations to represents the complex geometry on a fixed Cartesian mesh. Resolution issues for turbulent flows can be addressed by Large Eddy Simulation (LES) technique provided an accurate and robust Subgrid Stress (SGS) model is available. Higher order of numerical accuracy schemes for turbulent flows can be maintained as well as the geometrical complexities can be rendered physically by combining LES with IBM. The proposed methodology is simple and ideally suited for the moving geometries involving no-slip walls with prescribed trajectories and locations. IBM is validated for the laminar flow past a heated cylinder in a channel and LES is validated for the turbulent lid-driven cavity flow. LES-IBM is then is used to render complex geometry of trapped vortex combustor to study fluid mixing inside trapped vortex cavity. To demonstrate the full potential of LES-IBM, a complex moving geometry problem of stator-rotor interaction is solved.

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