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Simulation of fluid-structure interaction using the boundary data immersion method with adaptive mesh refinement

INTERNATIONAL JOURNAL FOR NUMERICAL methodS IN FLUIDS 2024年第7期96卷 1156-1169页

作者： Wang, Yuan Ge, Wei Chinese Acad Sci Inst Proc Engn State Key Lab Mesosci & Engn Beijing Peoples R China Univ Chinese Acad Sci Sch Chem Engn Beijing Peoples R China

The fluid-structure interaction is simulated using the boundary data immersion method. As the fluid-structure interface is smeared in the smoothing region, deviations are incurred in fluid simulations. For compressible flow, high order difference schemes with more mesh cells for the stencils are usually employed to achieve high overall accuracy, but near interfaces it requires wider smoothing region of several mesh cells for computational stability and hence lowers its accuracy significantly. To address this issue, the proposed algorithm switches to lower order difference schemes near the interfaces and applies adaptive mesh refining there to compensate the accuracy loss. Implemented with Structured Adaptive Mesh Refinement Application Infrastructure (SAMRAI), the algorithm shows notable improvement in the overall accuracy and efficiency in cases such as channel flow and flow past a cylinder. The algorithm is used to simulate the shock wave past a fixed or free cylinder with Ma =2.67$$ =2.67 $$ and Re =1482$$ =1482 $$, which reveals the relaxation process and the temporal evolution of the drag coefficient, it goes through a valley and maintains at relatively high value for the fixed cylinder, while that of the free cylinder tends to decrease in fluctuation which is found to be caused by the interaction between the forward moving cylinder and vortexes in the unsteady wake. The boundary data immersion method smears the fluid-structure interface in the smoothing region and incurs deviations. The proposed algorithm switches to lower order difference schemes near the interfaces and applies adaptive mesh refining there to compensate the accuracy loss. image

关键词： adaptive mesh refinement boundary data immersion method compressible flow fluid-structure interaction

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Effect of the yaw angle on turbulent flow structures around the submarine model

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Journal of Hydrodynamics 2024年第3期36卷 421-434页

作者： Yi-jing Hu Yi Qu Qin Wu Biao Huang School of Mechanical Engineering Beijing Institute of TechnologyBeijing100081China Beijing Institute of Electronic System Engineering Beijing100854China

The objective of this paper is to investigate the turbulent flow structures around the submarine model and evaluate the effect of the yaw angle on the turbulent flow *** large eddy simulation based on the boundary data immersion method is used to *** computational domain consists of 1.2×10^(8)uniformly distributed Cartesian orthogonal grid nodes to capture the basic flow characteristics around the *** pressure coefficient,friction coefficient and wake velocity distribution are in good agreement with the experimental *** different types of vortex structures were mainly captured around the model,including horseshoe vortex,sail tip vortex and crossflow separation *** the increase of the yaw angle,the asymmetry of the horseshoe vortex and the tip vortex gradually increases,and the vortex strength of the vortex leg on the windward of the horseshoe vortex and the vortex strength of the tip vortex also increase *** the crossflow separation vortex,the flow separation zone gradually expands and migrates downstream with the increase of the yaw angle.

关键词： Vortex structure submarine model boundary data immersion method yaw angle

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Computational study on hemodynamic effects of left superior pulmonary vein resection and associated physiological changes in the left atrium after left upper lobectomy

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COMPUTER methodS IN BIOMECHANICS AND BIOMEDICAL ENGINEERING 2024年第2期27卷 167-178页

作者： Yi, Wentao Otani, Tomohiro Yoshida, Takuya Endo, Shunsuke Wada, Shiego Osaka Univ Grad Sch Engn Sci Toyonaka Osaka Japan Jichi Med Univ Saitama Med Ctr Saitama Japan

Left upper lobectomy (LUL) with left superior pulmonary vein (LSPV) resection alters the left atrium (LA) physiological states and LA hemodynamics associated with thrombosis, although this underlying mechanism is poorly understood. Therefore, we investigated the effects of LSPV resection and associated LA physiological changes on LA hemodynamics using four-dimensional computed tomography image-based computational simulations. Three cases were considered: the LA before and after LUL extracted from computed tomography images and artificial LSPV resection without physiological changes. Comparisons among the three cases demonstrated that physiological changes associated with LSPV resection are the possible factors that affect the LA hemodynamics after LUL.

关键词： Left atrium computational fluid dynamics four-dimensional computed tomography boundary data immersion method hemodynamics

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Characteristics of Laminar Separation Bubble With Varying Leading-Edge Shapes and Deflections of the Trailing-Edge Flap

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JOURNAL OF ENGINEERING FOR GAS TURBINES AND POWER-TRANSACTIONS OF THE ASME 2024年第10期146卷 101014-101014页

作者： Sarvankar, Sumit S. Sarkar, Drik Arasu, Adrin Issai Mistry, Chetankumar Sureshbhai Vadlamani, Nagabhushana Rao Indian Inst Technol Madras Dept Aerosp Engn Chennai 600036 Tamil Nadu India Indian Inst Technol Kharagpur Dept Mech Engn Kharagpur 721302 W Bengal India Indian Inst Technol Kharagpur Dept Aerosp Engn Kharagpur 721302 W Bengal India

A series of implicit large eddy simulations (ILES) is carried out to examine the characteristics of a leading edge (LE) separation bubble. The test case comprises a flat plate with an elliptic leading edge (ELE), which is equipped with a trailing edge flap. Simulations are carried out (a) at three different flap angles (20 deg, 30 deg, 90 deg) and (b) using two different geometries of ELE where the ratio of the semimajor to semiminor axis is set to either 2:1 or 4:1. The flap is modeled using the immersed boundary method, which is computationally economical as it avoids regenerating the grid for varying flap angles. The results show that (a) the flow separates at lower flap deflection angles with a decrease in the aspect ratio of the ELE from 4:1 to 2:1 (b) an increase in the flap angle promotes separation at the LE due to an increase in the blockage in the bottom passage and a subsequent increase in the flow incidence at the leading edge. Simulations are also carried out using the gamma - Re-theta transition model and comparisons are drawn against ILES and experiments. Although the qualitative trends predicted using both ILES and Reynolds-Averaged Navier-Stokes (RANS) agree with the experiments, both approaches predict relatively shorter separation bubbles. This is attributed to the excess flow blockage in experiments due to the support plates, which are not modeled in the simulations. Nevertheless, the results demonstrate the superior accuracy of ILES over the RANS model.

关键词： leading edge separation implicit large eddy simulations boundary data immersion method Kelvin-Helmholtz instability

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CHARACTERISTICS OF LAMINAR SEPARATION BUBBLE WITH VARYING LEADING-EDGE SHAPES AND DEFLECTIONS OF THE TRAILING-EDGE FLAP

CHARACTERISTICS OF LAMINAR SEPARATION BUBBLE WITH VARYING LE...

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8th Biennial ASME Gas Turbine India Conference (GTINDIA) - Power and Propulsion - A Sustainable Future

作者： Sarvankar, Sumit S. Sarkar, Drik Mistry, Chetankumar Sureshbhai Vadlamani, Nagabhushana Rao Indian Inst Technol Madras Chennai Tamil Nadu India Indian Inst Technol Kharagpur Kharagpur W Bengal India

ISBN: (纸本)9780791887721

A series of Implicit Large Eddy Simulations (ILES) is carried out to examine the characteristics of a leading edge (LE) separation bubble. The test case comprises a flat plate with an elliptic leading edge which is equipped with a trailing edge flap. Simulations are carried out (a) at three different flap angles (20 degrees, 30 degrees, 90 degrees) and (b) using two different geometries of Elliptic Leading Edge (ELE) where the ratio of the semi-major to semi-minor axis is set to either 2:1 or 4:1. The flap is modeled using the immersed boundary method which is computationally economical as it avoids regenerating the grid for varying flap angles. The results show that (a) the flow separates at lower flap deflection angles with a decrease in the aspect ratio of the ELE from 4:1 to 2:1 (b) an increase in the flap angle promotes separation at the LE due to an increase in the blockage in the bottom passage and a subsequent increase in the flow incidence at the leading edge. Simulations are also carried out using the gamma-Re-theta transition model and comparisons are drawn against ILES and experiments. Although the qualitative trends predicted using both ILES and Reynolds Averaged Navier-Stokes (RANS) are in agreement with the experiments, both approaches predict relatively shorter separation bubbles. This is attributed to the excess flow blockage in experiments due to the support plates which are not modeled in the simulations. Nevertheless, the results demonstrate the superior accuracy of ILES over the Reynolds Averaged Navier Stokes (RANS) model.

关键词： Leading Edge Separation Implicit Large Eddy Simulations boundary data immersion method Kelvin-Helmholtz instability

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Low-frequency acoustic-gravity wave emission generated by the vortex caused by a moving submerged cylinder

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APPLIED OCEAN RESEARCH 2024年 147卷

作者： Dong, Qingchen Zhao, Xin Huang, Biao Wang, Guoyu Beijing Inst Technol Sch Mech Engn Beijing 100081 Peoples R China Beijing Inst Technol Sch Aerosp Engn Beijing 100081 Peoples R China

Acoustic-gravity waves induced by a cylinder moving underwater are numerically calculated in this study. Based on a weak compressibility method, a boundary data immersion method (BDIM), and the acoustic-gravity wave governing equation, we derive an algorithm that calculates the acoustic-gravity waves induced by a body moving underwater. We conduct numerical calculations for two cases: a horizontal uniform moving cylinder with and without lateral oscillation. The frequency spectra of acoustic-gravity waves are calculated at different monitoring locations. Strong anisotropy phenomena are observed from the time series and frequency spectra of the velocity potential function and the dynamic pressure. At the upper and bottom boundaries, the spectrum of acoustic-gravity waves can be approximated as noise. At the left and right boundaries, in the case of a cylinder moving horizontally in a straight line, the frequency spectrum of the acoustic-gravity wave caused by vortices becomes a low-frequency line spectrum. After the cylinder is subjected to lateral oscillation, the low-frequency line spectrum becomes a combination of the low-frequency broadband spectrum and line spectrum.

关键词： Acoustic-gravity wave Underwater moving cylinder Weak compressibility method boundary data immersion method

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Numerical simulation for ice breaking and water entry of sphere

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OCEAN ENGINEERING 2022年 243卷 110198-110198页

作者： Ren, Huifei Zhao, Xin Beijing Inst Technol Beijing 100081 Peoples R China

A three-dimensional ice-water-structure interaction numerical model is developed to simulate the ice breaking and water entry of rigid spheres. The algorithm employs the boundary data immersion method (BDIM) to simulate the solid-fluid interactions, the volume of fluid (VOF) method to track the liquid-gas interface, and the bond-based peridynamics method to model the ice cover. For the water entry of spheres, a good agreement between numerical and experimental results has been obtained for the water-entry cavity evolution and the motion of spheres. For the interaction between a sphere and the ice cover, a good agreement between the present results and the previous numerical results has been obtained for the shape and number of cracks. The crack propagation path of the ice cover, the cavity shape, pressure and velocity field, as well as the motion of spheres during the ice breaking and water entry are analyzed. Results show that the ice load on spheres is much greater than water load during the ice breaking and water entry process. Effects of the ice thickness and elastic modulus of the ice cover, the impact velocity and the density of the spheres are also discussed.

关键词： Water entry Ice-structure interaction Volume of fluid method boundary data immersion method Peridynamics

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Numerical investigation of flow structures around the DARPA SUBOFF model

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OCEAN ENGINEERING 2021年 239卷 109866-109866页

作者： Qu, Yi Wu, Qin Zhao, Xin Huang, Biao Fu, Xiaoying Wang, Guoyu Beijing Inst Technol Sch Mech Engn Beijing 100081 Peoples R China Beijing Inst Technol Sch Aerosp Engn Beijing 100081 Peoples R China Sichuan Univ State Key Lab Hydraul & Mt River Engn Chengdu 610065 Peoples R China

A large eddy simulation (LES) of a fully appended SUBOFF model was performed by the boundary data immersion method (BDIM) with the Reynolds number of 1.2 x 10(7). Numerical simulation is carried out through Fortran-based code and the geometric structure used in this paper is an idealized submarine (DARPA SUBOFF, with appendages). The computational uniformly distributed orthogonal grids consist of approximately 108 million nodes and are used to capture all essential flow structures. The pressure coefficients and streamwise velocity distribution obtained by the large-eddy simulation (LES) are in good agreement with the experimental data. The objective of this paper is to evaluate the ability of BDIM to predict the flow over axisymmetric hull, to investigate the evolution of the junction and tip flows on the body of the SUBOFF. Three different types of large-scale vortex structures were found around the sail, including horseshoe vortex, hairpin vortex and necklace vortex. The different vortex identification methods, namely, omega criterion, Q criterion and Liutex method, are used to capture and analyze the formation mechanism of various vortex structures. Meanwhile, by extracting the rotation and shear relative parameter epsilon around the sail, it can be found that the rotation is dominant in the vortex distribution profile.

关键词： Vortex structure Liutex method DAPRA SUBOFF boundary data immersion method

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Numerical simulations for water entry of hydrophobic objects

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OCEAN ENGINEERING 2019年 190卷 106485-000页

作者： Shentu, Jizan Zhao, Tihao Li, Daqin Zhao, Xin Beijing Inst Technol Beijing 100081 Peoples R China

Based on the boundary data immersion method (BDIM) and the volume of fluid (VOF) method, the water entry process of hydrophobic objects is numerically simulated. The water crown, the cavity and the flow pattern are analyzed. In the present study, the cavity shape caused by the water entry and trajectories of objects are simulated by the numerical method. Simulation results are compared with experimental data, and the comparisons show that the present numerical approach has the ability to predict the complex process of water entry as well as the effects of the density of an object and entry velocity. Numerical results indicate that the depth of pinch-off increases as reducing the characteristic length of the cavity;the pinch-off time increases for the sphere with a larger density;the depth of cylinder, where occurs the cavity shape inversion behavior, is not affected by the entry velocity of the cylinder.

关键词： boundary data immersion method Volume of fluid method Cavity Water entry

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