Effective Geometric Algorithms for Immersed Boundary Method Using Signed Distance Field

2018 ◽  
Vol 141 (6) ◽  
Author(s):  
Chenguang Zhang ◽  
Chunliang Wu ◽  
Krishnaswamy Nandakumar
Keyword(s):  
Immersed Boundary Method ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Closed Surface ◽  
Immersed Boundary ◽  
Field Calculation ◽  
Distance Field ◽  
Signed Distance ◽  
Boundary Method ◽  
Signed Distance Field

We present three algorithms for robust and efficient geometric calculations in the context of immersed boundary method (IBM), including classification of mesh cells as inside/outside of a closed surface, projection of points onto a surface, and accurate calculation of the solid volume fraction field created by a closed surface overlapping with a background Cartesian mesh. The algorithms use the signed distance field (SDF) to represent the surface and remove the intersection tests, which are usually required by other algorithms developed before, no matter the surface is described in analytic or discrete form. The errors of the algorithms are analyzed. We also develop an approximate method on efficient SDF field calculation for complex geometries. We demonstrate how the algorithms can be implemented within the framework of IBM with a volume-average discrete-forcing scheme and applied to simulate fluid–structure interaction problems.

An Efficient Immersed Boundary Method Based on Penalized Direct Forcing for Simulating Flows Through Real Porous Media

2012 ◽  
Author(s):  
Wim-Paul Breugem ◽  
Vincent van Dijk ◽  
René Delfos
Keyword(s):  
Porous Medium ◽  
Ct Scan ◽  
Immersed Boundary Method ◽  
Volume Fraction ◽  
Solid Volume Fraction ◽  
Particle Diameter ◽  
Immersed Boundary ◽  
Average Particle ◽  
Boundary Method ◽  
Direct Forcing

A computationally efficient Immersed Boundary Method (IBM) based on penalized direct forcing was employed to determine the permeability of a real porous medium. The porous medium was composed of about 9000 glass beads with an average particle diameter of 1.93 mm and a porosity of 0.367. The forcing of the IBM depends on the local solid volume fraction within a computational grid cell. The latter could be obtained from a high-resolution X-ray Computed Tomography (CT) scan of the packing. An experimental facility was built to determine the permeability of the packing experimentally. Numerical simulations were performed for the same packing based on the data from the CT scan. For a scan resolution of 0.1 mm the numerical value for the permeability was nearly 70% larger than the experimental value. An error analysis indicated that the scan resolution of 0.1 mm was too coarse for this packing.

Application of a Cartesian-Grid Immersed Boundary Method to 3D In-Cylinder Flow

2012 ◽  
Author(s):  
Claudia Günther ◽  
Matthias Meinke ◽  
Wolfgang Schröder
Keyword(s):  
Level Set ◽  
Immersed Boundary Method ◽  
Three Dimensional ◽  
Cartesian Grid ◽  
Distance Functions ◽  
Immersed Boundary ◽  
Splitting Algorithm ◽  
Signed Distance ◽  
Boundary Method ◽  
Cylinder Flow

In this work, a Cartesian-grid immersed boundary method using a cut-cell approach is applied to three-dimensional in-cylinder flow. A hierarchically coupled level-set solver is used to capture the boundary motion by a signed distance function. Topological changes in the geometry due to the opening and closing events of the valves are modeled consistently using multiple signed distance functions for the different components of the engine and taking advantage of a level-set reinitialization method. A continuous discretization of the flow equations in time near the moving interfaces is used to prevent nonphysical oscillations. To ensure an efficient implementation, independent grid adaptation for the flow and the level-set grid is applied. A narrow band approach and an efficient joining/splitting algorithm for the level-set functions minimize the computational overhead to track multiple interfaces. The ability of the current method to handle complex 3D setups is demonstrated for the interface capturing and the flow solution in a three-dimensional piston engine geometry.

Direct Simulation of Dense Suspensions of Non-Spherical Particles

2011 ◽  
Author(s):  
Orest Shardt ◽  
Jos Derksen
Keyword(s):  
Reynolds Number ◽  
Red Blood Cells ◽  
Sedimentation Rate ◽  
Immersed Boundary Method ◽  
Blood Cells ◽  
Volume Fraction ◽  
Immersed Boundary ◽  
Direct Simulation ◽  
Rigid Particles ◽  
Boundary Method

We describe the direct simulation of high-solids-fraction suspensions of non-spherical rigid particles that are slightly denser than the fluid. The lattice-Boltzmann method is used to solve the flow of the interstitial Newtonian fluid, and the immersed boundary method is used to enforce a no-slip boundary condition at the surface of each particle. The surface points for the immersed boundary method are also employed for collision handling by applying repulsive forces between nearby surface points. Due to the finite number of these points, the method simulates rough surface collisions. We also discuss methods for integrating the equations of particle motion at low density ratios and propose a method with improved accuracy. Rigid particles shaped like red blood cells were simulated. Simulations of a single particle showed that the particle settles in its original orientation when the Reynolds number is low (1.2) but flips to a higher drag orientation when the Reynolds number is higher (7.3). A simulation with a 45% solids volume fraction and a low solid over fluid density ratio showed the possibility of simulating blood as it is found in the body. A simulation at a lower solids volume fraction (35%) was used to compare the results with the erythrocyte sedimentation rate (ESR), a common blood test. The sedimentation rate was estimated as 0.2 mm/hr, which is an order of magnitude lower than a typical ESR of about 6 mm/hr for a healthy adult. The most likely reasons for the discrepancy are the omission of agglomeration-inducing inter-cellular forces from the simulations and the treatment of the red blood cells as rigid particles.

scholarly journals An Immersed Boundary Method Based on Volume Fraction

2015 ◽  
Vol 99 ◽  
pp. 677-685 ◽  
Author(s):  
Yuelong He ◽  
Dun Li ◽  
Shuai Liu ◽  
Handong Ma
Keyword(s):  
Immersed Boundary Method ◽  
Volume Fraction ◽  
Immersed Boundary ◽  
Boundary Method

scholarly journals A POROUS VISCOELASTIC MODEL FOR THE CELL CYTOSKELETON

2018 ◽  
Vol 59 (4) ◽  
pp. 472-498 ◽  
Author(s):  
CALINA A. COPOS ◽  
ROBERT D. GUY
Keyword(s):  
Immersed Boundary Method ◽  
Cell Biology ◽  
Numerical Solutions ◽  
Volume Fraction ◽  
Viscoelastic Model ◽  
Extracellular Fluid ◽  
Microfluidic Channel ◽  
Maxwell Model ◽  
Immersed Boundary ◽  
Boundary Method

The immersed boundary method is a widely used mixed Eulerian/Lagrangian framework for simulating the motion of elastic structures immersed in viscous fluids. In this work, we consider a poroelastic immersed boundary method in which a fluid permeates a porous, elastic structure of negligible volume fraction, and extend this method to include stress relaxation of the material. The porous viscoelastic method presented here is validated for a prescribed oscillatory shear and for an expansion driven by the motion at the boundary of a circular material by comparing numerical solutions to an analytical solution of the Maxwell model for viscoelasticity. Finally, an application of the modelling framework to cell biology is provided: passage of a cell through a microfluidic channel. We demonstrate that the rheology of the cell cytoplasm is important for capturing the transit time through a narrow channel in the presence of a pressure drop in the extracellular fluid.

An New Immersed Boundary Method With Level Set Based Geometry Representation and Volume Fraction Based Body Force Calculation

2018 ◽  
Author(s):  
Guangfa Yao
Keyword(s):  
Level Set ◽  
Immersed Boundary Method ◽  
Body Force ◽  
Volume Fraction ◽  
The Body ◽  
Immersed Boundary ◽  
Immersed Boundary Methods ◽  
Boundary Method ◽  
Boundary Methods ◽  
Fluid Solid Interaction

Immersed boundary method has got increasing attention in modeling fluid-solid interaction using computational fluid dynamics due to its robustness and simplicity. It simulates fluid-solid interaction by adding a body force in the momentum equation without a body conforming mesh generation involved. Different immersed boundary methods have been presented and applied to solve fluid flow with immersed solid bodies. The main difference between these immersed boundary methods is how the body force is calculated. In this paper, a new immersed boundary method is proposed. The body force is calculated based on the volume fraction of the solid body immersed in fluid. Compared to the existing and similar methods, the new method develops a mechanism to calculate the body force and thereby more accurately resolve the physics on the solid-fluid interface. The solid body is represented using a level set that facilitates the calculation of the solid volume fraction. The body force derivation is presented and the method is validated against the test cases with existing analytical solutions or well established numerical solutions. A good match was reached.

scholarly journals An Immersed Boundary Geometric Preprocessor for Arbitrarily Complex Terrain and Geometry

2015 ◽  
Vol 32 (11) ◽  
pp. 2075-2087 ◽  
Author(s):  
Inanc Senocak ◽  
Micah Sandusky ◽  
Rey DeLeon ◽  
Derek Wade ◽  
Kyle Felzien ◽  
...  
Keyword(s):  
Immersed Boundary Method ◽  
Complex Terrain ◽  
Complex Geometry ◽  
Turbulence Models ◽  
Urban Environments ◽  
Immersed Boundary ◽  
Wind Fields ◽  
Geometric Information ◽  
Distance Field ◽  
Boundary Method

AbstractThere is a growing interest to apply the immersed boundary method to compute wind fields over arbitrarily complex terrain. The computer implementation of an immersed boundary module into an existing flow solver can be accomplished with minor modifications to the rest of the computer program. However, a versatile preprocessor is needed at the first place to extract the essential geometric information pertinent to the immersion of an arbitrarily complex terrain inside a 3D Cartesian mesh. Errors in the geometric information can negatively impact the correct implementation of the immersed boundary method as part of the solution algorithm. Additionally, the distance field from the terrain is needed to implement various subgrid-scale turbulence models and to initialize wind fields over complex terrain. Despite the popularity of the immersed boundary method, procedures used in the geometric preprocessing stage have received less attention. The present study found that concave and convex regions of complex terrain are particularly challenging to process with existing procedures discussed in the literature. To address this issue, a geometric preprocessor with a distance field solver was presented, and the solver demonstrated its versatility for arbitrarily complex geometry, terrain, and urban environments. The distance field solver uses the initial distance field at the immersed boundaries and propagates it to the rest of the domain by solving the Eikonal equation with the fast sweeping method.

scholarly journals Immersed boundary method for MHD unsteady natural convection around a hot elliptical cylinder in a cold rhombus enclosure filled with a nanofluid

2021 ◽  
Vol 3 (2) ◽  
Author(s):  
Ali Akbar Hosseinjani ◽  
Amir H. Roohi
Keyword(s):  
Magnetic Field ◽  
Nusselt Number ◽  
Natural Convection ◽  
Immersed Boundary Method ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Magnetic Field Effect ◽  
Elliptical Cylinder ◽  
Immersed Boundary ◽  
Boundary Method

AbstractIn this study, the numerical investigation of the natural convection heat transfer around a hot elliptical cylinder inside a cold rhombus enclosure filled with a nanofluid in the presence of a uniform magnetic field is conducted. An immersed boundary method as a computational tool has been extended and applied to solve the problem. The influence of various parameters such as cylinder diameters (a, b), Hartmann number (Ha = 0, 50 and 100), nanofluid volume fraction ($$\varphi = 0 , 2.5\% and 5\%$$ φ = 0 , 2.5 % a n d 5 % ), and Rayleigh number (Ra = 103, 104, 105, 106, and 107) has been studied. Streamlines and isotherms contours as well as average Nusselt number have been specified for different modes. An equation for the average Nusselt number as a function of mentioned parameters is presented in this paper. The results show that at lower Ra numbers of Ra = 103 and 104, the magnetic field effect is negligible. However, at higher Rayleigh numbers, the average Nusselt number (Nuave) decreases with the increasing Ha number. The maximum decrease in Nuave at Ra = 105, 106 and 107are calculated −8.15%, −23.4% and −27.3%, respectively. An asymmetry-unsteady flow is observed at $${\text{Ra}} = 10^{7}$$ Ra = 10 7 for Ha = 0. However, at higher Ha numbers a steady-symmetrical flow is formed.

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