A Sharp-Interface Immersed Boundary Method for Simulating Incompressible Flows with Arbitrarily Deforming Smooth Boundaries

2017 ◽  
Vol 15 (01) ◽  
pp. 1750080 ◽  
Author(s):  
Zuo Cui ◽  
Zixuan Yang ◽  
Hong-Zhou Jiang ◽  
Wei-Xi Huang ◽  
Lian Shen
Keyword(s):  
Incompressible Flows ◽  
Deformable Body ◽  
Fluid Flows ◽  
Sharp Interface ◽  
Immersed Boundary ◽  
Time Step ◽  
Fluid Forces ◽  
Solid Bodies ◽  
Ib Method ◽  
Moving Bodies

We develop a sharp interface immersed boundary (IB) method to simulate the interactions between fluid flows and deformable moving bodies. Fluid–solid interfaces are captured using a level-set (LS) function, which is updated at every time step by a reinitialization procedure. Motions of solid bodies are dynamically coupled with fluid flows by calculating the fluid forces exerted on solid bodies. The accuracy and robustness of the LS-based IB method are tested systematically in the context of several benchmark cases and self-propelled fish swimming. The effects of computational parameters on the accuracy of deformable body capturing are analyzed. It is found that the algorithm performs well in simulating the flow motions surrounding the deforming and moving bodies.

Studying the deployment of high-lift devices by using dynamic immersed boundaries

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Francesco Capizzano ◽  
Triyantono Sucipto
Keyword(s):  
Research Effort ◽  
Logical Consequence ◽  
Least Square ◽  
Immersed Boundary ◽  
Computational Domain ◽  
Time Step ◽  
High Lift ◽  
Content Type ◽  
Moving Least Square ◽  
Ib Method

Purpose This paper aims to describe a research effort towards the comprehension of the unsteady phenomena due to the deployment of high-lift devices at approach/landing conditions. Design/methodology/approach The work starts from a preexisting platform based on an immersed boundary (IB) method whose capabilities are extended to study compressible and viscous flows around moving/deforming objects. A hybrid Lagrangian-Eulerian approach is designed to consider the motion of multiple bodies through a fixed Cartesian mesh. That is, the cells’ volumes do not move in space but rather they observe the solid walls crossing themselves. A dynamic discrete forcing makes use of a moving least-square procedure which has been validated by simulating well-known benchmarks available for rigid body motions. Partitioned fluid-structure interactions (FSI) strategies are explored to consider aeroelastic phenomena. A shared platform, between the aerodynamic and the structural solvers, fulfils the loads’ transfer and drives the sequence of the operating steps. Findings The first part of the results is devoted to a basic two-dimensional study aiming at evaluating the accuracy of the method when simple rigid motions are prescribed. Afterwards, the paper discusses the solution obtained when applying the dynamic IB method to the rigid deployment of a Krueger-flap. The final section discusses the aeroelastic behaviour of a three-element airfoil during its deployment phase. A loose FSI coupling is applied for estimating the possible loads’ downgrade. Research limitations/implications The IB surfaces are allowed to move less than one IB-cell size at each time-step de-facto restricting the Courant-Friedrichs-Lewy (CFL) based on the wall velocity to be smaller than unity. The violation of this constraint would impair the explicit character of the method. Practical implications The proposed method improves automation in FSI numerical analysis and relaxes the human expertise/effort for meshing the computational domain around complex three-dimensional geometries. The logical consequence is an overall speed-up of the simulation process. Originality/value The value of the paper consists in demonstrating the applicability of dynamic IB techniques for studying high-lift devices. In particular, the proposed Cartesian method does not want to compete with body-conforming ones whose accuracy remains generally superior. Rather, the merit of this research is to propose a fast and automatic simulation system as a viable alternative to classic multi-block structured, chimaera or unstructured tools.

Efficiency of Diffuse and Sharp Interface Strongly Coupled Fluid Structure Interaction Methods in Fixed and Moving Boundaries

2016 ◽  
Author(s):  
Fazlolah Mohaghegh ◽  
H. S. Udaykumar
Keyword(s):  
Fluid Structure Interaction ◽  
Mass Effect ◽  
Sharp Interface ◽  
Diffuse Interface ◽  
Immersed Boundary ◽  
Immersed Boundary Methods ◽  
Time Step ◽  
Fluid Structure ◽  
Strongly Coupled ◽  
Structure Interaction

Efficiency of different types of immersed boundary methods in the fluid structure interaction (FSI) analysis is studied for different cases. Two different formulations of smoothed profile method (SPM) [1, 2] as diffuse interface approaches are compared with the ghost fluid method (GFM) [3, 4] as sharp interface method (SIM) [5]. First, the original SPM which has two pressure Poisson equations (SPM2P) is modified to a novel formulation for SPM with only one pressure Poisson equation (SPM1P) and then validated. The efficiency study is performed for SPM1P, SPM2P and SIM. The results show that when the solid object is fixed, the explicit solution of SIM is faster than the two SPMs. However, when the solid is moving and strongly coupled formulations is used, SPM1P will be the fastest method. It is shown that the efficiency of the strongly coupled formulations depends on the number of subiterations required in each time step to reach the converged implicit solution. SPM1P and SPM2P need less number of subiterations in comparison with SIM and they are faster. When the added mass effect is high, the efficiency of SPM becomes more noticeable as the required number of subiterations is significantly less in SPM. Finally, SPM1P is faster than SPM2P in all cases however, the accuracy of SPM2P in predicting the flow pattern is better than SPM1P.

Mass Conservation in the Immersed Boundary Method

2005 ◽  
Author(s):  
Frank Muldoon ◽  
Sumanta Acharya
Keyword(s):  
Boundary Conditions ◽  
Immersed Boundary Method ◽  
Incompressible Flows ◽  
Mass Conservation ◽  
Steady State Solution ◽  
Immersed Boundary ◽  
Governing Equations ◽  
Time Step ◽  
Backward Euler ◽  
Divergence Free

The immersed boundary approach for the modeling of complex geometries in incompressible flows is examined critically from the perspective of satisfying boundary conditions and mass conservation. The system of discretized equations for mass and momentum can be inconsistent if the real velocities are used in defining the forcing terms used to satisfy the boundary conditions. As a result, the velocity is generally not divergence free and the pressure at locations in the vicinity of the immersed boundary is not physical. However, the use of the pseudo velocities in defining the forcing (as frequently done when the governing equations are solved using a fractional step or projection method) combined with the use of the specified velocity on the immersed boundary is shown to result in a consistent set of equations which allows a divergence free velocity but, depending on the time step used to obtain a steady state solution, is shown to have an undesirable effect of allowing significant permeability of the immersed boundary. An improvement is shown if the pressure gradient is integrated in time using the Crank-Nicholson scheme instead of the backward Euler scheme. However, even with this improvement a significant reduction in the time step and hence increase in computational expense is still required for sufficient satisfaction of the boundary conditions.

Pressure Correction Method for Simulating Solid-Fluid Mixture Flow

2011 ◽  
Author(s):  
San-Yih Lin ◽  
Ya-Hsien Chin ◽  
Yi-Cheng Chen
Keyword(s):  
Particle Interaction ◽  
Three Dimensional ◽  
Correction Method ◽  
Immersed Boundary ◽  
Time Step ◽  
Fluid Mixture ◽  
Mixture Flow ◽  
Pressure Correction ◽  
Step Algorithm ◽  
Solid Bodies

A pressure correction method is developed to simulate fluid-particle interaction flows. In this Paper, the three-dimensional solid-fluid mixture flows are investigated. The pressure corrected method coupled with the direct-forcing immersed boundary (IB) and the volume of fluid (VOF) methods is used to simulate the mixture flows. A discrete element method (DEM) together with a multi-time-step algorithm is introduced into the pressure correction method to calculate the forces and torques between solid bodies and between solid bodies and walls. As a demonstration of the efficient and capabilities of the present method, four test cases are simulated. They include sedimentation of one spherical particle in an enclosure, collapse of six solid-cylinder layers, two-dimensional solid-fluid mixture flow, and three-dimensional solid-fluid mixture flow.

An Efficient Immersed-Boundary Method to Deal With Over 1000 Solid Particles in Liquid Flow

2003 ◽  
Author(s):  
Takeo Kajishima
Keyword(s):  
Immersed Boundary Method ◽  
Solid Particles ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Flow Conditions ◽  
Particle Rotation ◽  
Navier Stokes Equation ◽  
Fluid Forces ◽  
Boundary Method ◽  
Solid Bodies

To deal with a number of solid bodies moving in fluid flow, we proposed an immersed-boundary method, in which the fortified Navier-Stokes equation was applied (Kajishima, et al., 2001). The fluid forces on the bodies are obtained by resolving flow around them. In this paper, some improvement for wider variety of flow conditions is introduced. Then a result of direct numerical simulation (DNS) of turbulence caused by over 1024 particles falling by gravity is demonstrated with particular interest on the influence of particle rotation.

scholarly journals A versatile sharp interface immersed boundary method for incompressible flows with complex boundaries

2008 ◽  
Vol 227 (10) ◽  
pp. 4825-4852 ◽  
Author(s):  
R. Mittal ◽  
H. Dong ◽  
M. Bozkurttas ◽  
F.M. Najjar ◽  
A. Vargas ◽  
...  
Keyword(s):  
Immersed Boundary Method ◽  
Incompressible Flows ◽  
Sharp Interface ◽  
Immersed Boundary ◽  
Boundary Method ◽  
Complex Boundaries

Lattice-BGK Methods for Simulating Incompressible Fluid Flows

1997 ◽  
Vol 08 (04) ◽  
pp. 793-803 ◽  
Author(s):  
Yu Chen ◽  
Hirotada Ohashi
Keyword(s):  
Fluid Flow ◽  
Incompressible Fluid ◽  
Poisson Equation ◽  
General Model ◽  
Incompressible Flows ◽  
Fluid Flows ◽  
Incompressible Limit ◽  
Numerical Example ◽  
Incompressible Fluid Flows

The lattice-Bhatnagar-Gross-Krook (BGK) method has been used to simulate fluid flow in the nearly incompressible limit. But for the completely incompressible flows, two special approaches should be applied to the general model, for the steady and unsteady cases, respectively. Introduced by Zou et al.,1 the method for steady incompressible flows will be described briefly in this paper. For the unsteady case, we will show, using a simple numerical example, the need to solve a Poisson equation for pressure.

Volume preserving immersed boundary methods for two-phase fluid flows

2011 ◽  
Vol 69 (4) ◽  
pp. 842-858 ◽  
Author(s):  
Yibao Li ◽  
Eunok Jung ◽  
Wanho Lee ◽  
Hyun Geun Lee ◽  
Junseok Kim
Keyword(s):  
Fluid Flows ◽  
Immersed Boundary ◽  
Immersed Boundary Methods ◽  
Two Phase ◽  
Boundary Methods ◽  
Phase Fluid ◽  
Volume Preserving
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