scholarly journals Numerical Investigation of Freely Falling Objects Using Direct-Forcing Immersed Boundary Method

Mathematics ◽  
2020 ◽  
Vol 8 (9) ◽  
pp. 1619
Author(s):  
Cheng-Shu You ◽  
Ming-Jyh Chern ◽  
Dedy Zulhidayat Noor ◽  
Tzyy-Leng Horng
Keyword(s):  
Stokes Equations ◽  
Control Volume ◽  
Equations Of Motion ◽  
Numerical Test ◽  
Free Fall ◽  
Immersed Boundary ◽  
Solid Objects ◽  
Regular Triangle ◽  
Direct Forcing ◽  
Circular Disks

The fluid-structure interaction of solid objects freely falling in a Newtonian fluid was investigated numerically by direct-forcing immersed boundary (DFIB) method. The Navier–Stokes equations are coupled with equations of motion through virtual force to describe the motion of solid objects. Here, we rigorously derived the equations of motion by taking control-volume integration of momentum equation. The method was validated by a popular numerical test example describing the 2D flow caused by the free fall of a circular disk inside a tank of fluid, as well as 3D experimental measurements in the sedimentation of a sphere. Then, we demonstrated the method by a few more 2D sedimentation examples: (1) free fall of two tandem circular disks showing drafting, kissing and tumbling phenomena; (2) sedimentation of multiple circular disks; (3) free fall of a regular triangle, in which the rotation of solid object is significant; (4) free fall of a dropping ellipse to mimic the falling of a leaf. In the last example, we found rich falling patterns exhibiting fluttering, tumbling, and chaotic falling.

The Flow of A Falling Ellipse: Numerical Method and Classification

2015 ◽  
Vol 31 (6) ◽  
pp. 771-782 ◽  
Author(s):  
R.-J. Wu ◽  
S.-Y. Lin
Keyword(s):  
Reynolds Number ◽  
Stokes Equations ◽  
Correction Method ◽  
Navier Stokes ◽  
Immersed Boundary ◽  
Two Dimensional ◽  
Inertia Moment ◽  
Navier Stokes Equations ◽  
Direct Forcing ◽  
Ib Method

AbstractA modified direct-forcing immersed-boundary (IB) pressure correction method is developed to simulate the flows of a falling ellipse. The pressure correct method is used to solve the solutions of the two dimensional Navier-Stokes equations and a direct-forcing IB method is used to handle the interaction between the flow and falling ellipse. For a fixed aspect ratio of an ellipse, the types of the behavior of the falling ellipse can be classified as three pure motions: Steady falling, fluttering, tumbling, and two transition motions: Chaos, transition between steady falling and fluttering. Based on two dimensionless parameters, Reynolds number and the dimensionless moment of inertia, a Reynolds number-inertia moment phase diagram is established. The behaviors and characters of five falling regimes are described in detailed.

scholarly journals MOTION OF SOLID SPHERES UNDER SOLITARY WAVE ATTACK: PHYSICAL AND NUMERICAL MODELING

2018 ◽  
pp. 81
Author(s):  
Hasan Gokhan Guler ◽  
Taro Arikawa ◽  
Cuneyt Baykal ◽  
Koray Deniz Göral ◽  
Ahmet Cevdet Yalciner
Keyword(s):  
Numerical Model ◽  
Solitary Wave ◽  
Physical Model ◽  
Stokes Equations ◽  
Equations Of Motion ◽  
Numerical Test ◽  
Ocean Engineering ◽  
Engineering Research ◽  
Model Experiments ◽  
Solid Spheres

In this study, physical and numerical test are carried out focusing on the motion of two solid spheres under solitary wave attack. The numerical model CADMAS-SURF/3D-2F-DEM coupling a multiphase flow solver solving Reynolds Averaged Navier-Stokes Equations based on a porous body model and a discrete element method solver for Newton’s equations of motion is validated against the data of physical model experiments carried out in the wave flume of METU Ocean Engineering Research Center. Comparisons of the numerical simulations and physical model experiments show that the numerical model is capable of simulating the motion of solid spheres under solitary wave attack in a reasonably well accuracy.

Interaction Between Multiple Solid Objects and Bubbles

2010 ◽  
Author(s):  
Ryuichi Iwata ◽  
Takeo Kajishima ◽  
Shintaro Takeuchi
Keyword(s):  
Numerical Method ◽  
Volume Of Fluid ◽  
Solid Particles ◽  
Immersed Boundary ◽  
Particle Interactions ◽  
Volume Of Fluid Method ◽  
Rising Bubble ◽  
Solid Objects ◽  
Multiple Particles ◽  
Particle Laden Flows

In the present study, bubble-particle interactions in suspensions are investigated by a coupled immersed-boundary and volume-of-fluid method (IB-VOF method), which is proposed by the present authors. The validity of the numerical method is examined through simulations of a rising bubble in a liquid and a falling particle in a liquid. Dilute particle-laden flows and a gas-liquid-solid flow involving solid particles and bubbles of comparable sizes to one another (Db/Dp = 1) are simulated. Drag coefficients of particles in particle-laden flows are estimated and flow fields involving multiple particles and a bubble are demonstrated.

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.

Numerical Investigation of the Coulter Principle in a Microfluidic Device

2013 ◽  
Author(s):  
Muheng Zhang ◽  
Yongsheng Lian
Keyword(s):  
Electric Field ◽  
Stokes Equations ◽  
Equations Of Motion ◽  
Navier Stokes ◽  
Working Mechanism ◽  
Navier Stokes Equations ◽  
Sheath Flow ◽  
Coulter Counters ◽  
Pass Through ◽  
Cell Motion

Coulter counters are analytical microfluidic instrument used to measure the size and concentration of biological cells or colloid particles suspended in electrolyte. The underlying working mechanism of Coulter counters is the Coulter principle which relies on the fact that when low-conductive cells pass through an electric field these cells cause disturbances in the measurement (current or voltage). Useful information about these cells can be obtained by analyzing these disturbances if an accurate correlation between the measured disturbances and cell characteristics. In this paper we use computational fluid dynamics method to investigate this correlation. The flow field is described by solving the Navier-Stokes equations, the electric field is represented by a Laplace’s equation in which the conductivity is calculated from the Navier-Stokes equations, and the cell motion is calculated by solving the equations of motion. The accuracy of the code is validated by comparing with analytical solutions. The study is based on a coplanar Coulter counter with three inlets that consist of two sheath flow inlet and one conductive flow inlet. The effects of diffusivity, cell size, sheath flow rate, and cell geometry are discussed in details. The impacts of electrode size, gap between electrodes and electrode location on the measured distribution are also studied.

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