Article
Mathematics, Applied
Marco Bravin, Sarka Necasova
Summary: In this paper, the evolution of a small rigid body in a viscous incompressible fluid is studied. It is shown that a small particle is not accelerated by the fluid as its size approaches zero under a lower bound on its mass. This result is based on a new a priori estimate on the velocities of the centers of mass of rigid bodies, even when their masses are allowed to decrease to zero.
JOURNAL OF DYNAMICS AND DIFFERENTIAL EQUATIONS
(2023)
Article
Computer Science, Interdisciplinary Applications
Xinjie Ji, James Gabbard, Wim M. van Rees
Summary: This paper introduces a sharp-interface approach based on the immersed interface method for handling the one- and two-way coupling between an incompressible flow and rigid bodies using the vorticity-velocity Navier-Stokes equations. The authors develop a moving boundary treatment and a two-way coupling methodology that do not require the pressure field. Extensive testing shows that the resulting solver achieves second-order accuracy and provides efficiency benefits compared to a representative first-order approach.
JOURNAL OF COMPUTATIONAL PHYSICS
(2023)
Article
Multidisciplinary Sciences
Yuexia Luna Lin, Nicholas J. Derr, Chris H. Rycroft
Summary: The numerical method presented is specifically designed for simulating three-dimensional fluid-structure interaction problems based on the reference map technique. It simplifies the meshing of complex geometries typical in FSI simulations and greatly simplifies the coupling between fluids and solids. Through parallelization and a field extrapolation scheme, the method demonstrates efficiency and accuracy in simulating incompressible FSI with neo-Hookean solids.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2022)
Article
Computer Science, Interdisciplinary Applications
J. Antoon van Hooft, Stephane Popinet
Summary: This article presents a numerical solver for the incompressible Navier-Stokes equations. The solver combines fourth-order-accurate discrete approximations and an adaptive tree grid to achieve high accuracy and efficiency. The solver employs a novel compact-upwind advection scheme and a 4th-order accurate projection algorithm to satisfy the incompressibility constraint. The paper also introduces a new refinement indicator tailored to this solver and demonstrates the consistency and convergence rate of the adaptive solver through tests and examples.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Computer Science, Interdisciplinary Applications
Lingquan Li, Rainald Lohner, Aditya K. Pandare, Hong Luo
Summary: In this paper, a robust and efficient finite volume method with interface sharpening technique is proposed to solve the six-equation multi-fluid single-pressure model for compressible two-phase flows. The performance of the method is evaluated through benchmark test cases, demonstrating its accuracy and efficiency.
JOURNAL OF COMPUTATIONAL PHYSICS
(2022)
Article
Engineering, Multidisciplinary
Shinhoo Kang, Emil M. Constantinescu, Hong Zhang, Robert L. Jacob
Summary: Earth system models consist of coupled components modeling systems like the global atmosphere, ocean, and land surface. This study focuses on the challenges of coupling these components, including computational efficiency, accuracy, and stability, exploring tight and loose coupling strategies for handling different time scales. Numerical experiments demonstrate the stability and mass conservation of the coupling schemes in a simplified model for the air-sea interaction problem with compressible Navier-Stokes equations.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Mathematics
Mads Kyed
Summary: This study establishes the existence of weak time-periodic solutions to the Navier-Stokes equations in three dimensional whole-space with time-periodic forcing terms. The solutions are constructed in such a way that the structural properties of their kinetic energy are obtained, without any restrictions on either the size or structure of the external force.
Article
Operations Research & Management Science
Elisabeth Diehl, Johannes Haubner, Michael Ulbrich, Stefan Ulbrich
Summary: In this paper, optimal control problems for two-phase Navier-Stokes equations with surface tension are analyzed. By utilizing the L-p-maximal regularity of the linear problem and recent well-posedness results for small data, the differentiability of the solution with respect to controls is demonstrated. The study incorporates formulations transforming the interface to a hyperplane, deducing differentiability results in physical coordinates, and deriving sensitivity equations of a Volume-of-Fluid type formulation.
COMPUTATIONAL OPTIMIZATION AND APPLICATIONS
(2022)
Article
Engineering, Multidisciplinary
R. Chabiniok, J. Hron, A. Jarolimova, J. Malek, K. R. Rajagopal, K. Rajagopal, H. Svihlova, K. Tuma
Summary: This study aims to understand the flow characteristics of three-dimensional incompressible Navier-Stokes fluid in tubes with a sinusoidal extension. The research is significant for its implications on blood flow through the aortic root, and reveals variations in flow attributes under different slip conditions.
INTERNATIONAL JOURNAL OF ENGINEERING SCIENCE
(2022)
Article
Mathematics, Applied
Ai-Li Yang, Jun-Li Zhu, Yu-Jiang Wu
Summary: For a class of three-by-three block systems of linear equations, a multi-parameter dimensional split (MPDS) preconditioner is developed to accelerate the convergence of the Krylov subspace methods. An effective method for computing the optimal parameters is proposed. Numerical examples demonstrate the robustness and efficiency of the MPDS preconditioner for Navier-Stokes equations and PDE constraint optimization problems.
NUMERICAL ALGORITHMS
(2023)
Article
Mathematics, Applied
Kyungkeun Kang, Hwa Kil Kim, Jae-Myoung Kim
Summary: We investigate the Cauchy problem for the coupled system of Vlasov and non-Newtonian fluid equations. We establish the local well-posedness of strong solutions, assuming sufficiently regular initial data.
ZEITSCHRIFT FUR ANGEWANDTE MATHEMATIK UND PHYSIK
(2023)
Article
Computer Science, Interdisciplinary Applications
Yanyao Wu, Junxiang Yang, Zhijun Tan
Summary: In this work, we study a phase-field fluid-surfactant system using conservative Allen-Cahn equations and Navier-Stokes equations. We propose a highly efficient numerical scheme based on scalar auxiliary variables, which decouple all the variables and allow for step-by-step updates. The method satisfies mass conservation, unique solvability, and modified energy dissipation. Tests are conducted to investigate surfactant-laden phase separation and its effects in two and three-dimensional spaces.
COMPUTER PHYSICS COMMUNICATIONS
(2023)
Article
Computer Science, Interdisciplinary Applications
Afsoun Rahnama Falavarjani, David Salac
Summary: Many multiphase fluid systems exhibit a breakdown of the no-slip condition at the material interface, causing a difference in tangential velocity between the inner and outer fluid. A numerical model is presented to investigate these systems in both two- and three-dimensions, using a hybrid Navier-Stokes projection method and the Immersed Interface Method. The model shows excellent agreement with experimental and computational results, and is able to explore the influence of interfacial slip in various multiphase fluid systems.
JOURNAL OF COMPUTATIONAL PHYSICS
(2023)
Article
Mathematics, Applied
Mehdi Badra, Takeo Takahashi
Summary: This paper investigates the interaction between a viscous incompressible fluid and an elastic structure. By studying the linearized system, the existence of strong solutions for the coupled system is shown, and the corresponding semigroup is proven to be analytic. This result is compared to the case where the elastic displacement is governed by a beam equation, which only yields a Gevrey class semigroup.
JOURNAL OF EVOLUTION EQUATIONS
(2022)
Article
Mechanics
Li-Wei Chen, Berkay A. Cakal, Xiangyu Hu, Nils Thuerey
Summary: In this study, deep learning methods were used to efficiently predict flow fields and loads for aerodynamic shape optimization. The trained U-net-based deep neural network models successfully inferred flow fields and calculated gradient flows for optimizing shapes, showing great promise for general aerodynamic design problems. The results demonstrate that the DNN models are capable of accurately predicting flow fields and generating satisfactory aerodynamic forces, even without specific training for aerodynamic forces.
JOURNAL OF FLUID MECHANICS
(2021)
Article
Computer Science, Interdisciplinary Applications
Trong-Nguyen Duy, Van-Tu Nguyen, Thanh-Hoang Phan, Warn-Gyu Park
Summary: An enhanced coupling method for interface computations in incompressible two-phase flows is presented in this paper. The estimated interface shows significant improvements in smoothness and accuracy compared to previous methods, demonstrating its potential for academic research and practical applications.
COMPUTERS & FLUIDS
(2021)
Article
Computer Science, Interdisciplinary Applications
Van-Tu Nguyen, Thanh-Hoang Phan, Trong-Nguyen Duy, Warn-Gyu Park
Summary: This study introduces an accurate shock- and interface-capturing method to simulate compressible multiphase flows with shockwaves using curvilinear body-fitted structured grids. By enhancing a five-equation model proficient in capturing unsteady shocks in compressible multiphase flows and developing a new eigensystem for conservation laws/Godunov-type finite volume scheme, strong shocks were effectively captured and analyzed. The results show good agreement with experimental data, indicating high impacts of primary blast waves on structures in complex scenarios.
COMPUTERS & FLUIDS
(2021)
Article
Mechanics
Thanh-Hoang Phan, Ebrahim Kadivar, Van-Tu Nguyen, Ould el Moctar, Warn-Gyu Park
Summary: This study investigates the thermodynamic effects on the dynamics of single cavitation bubbles using experimental and numerical methods. The results show that an increase in ambient temperature leads to nonspherical bubble shapes with jet flows during the rebound stage. Quantitative analysis of bubble behavior and intensity reveals that the maximum bubble radius, first minimum bubble radius, and collapsing time increase with increasing ambient temperature, while the peak values of internal pressure and temperature decrease.
Article
Computer Science, Interdisciplinary Applications
Van-Tu Nguyen, Thanh-Hoang Phan, Trong-Nguyen Duy, Dong-Hyun Kim, Warn-Gyu Park
Summary: We propose a fully compressible multiphase model for simulating compressible interfacial flows. The model is based on the typical conservation laws for mixtures and is solved using a high-resolution shock-capturing finite-volume method. It can maintain sharp interfaces and achieve high accuracy, conservation properties, and thermodynamic consistency.
COMPUTERS & FLUIDS
(2022)
Article
Thermodynamics
Thanh-Hoang Phan, Van-Tu Nguyen, Trong-Nguyen Duy, Dong-Hyun Kim, Warn-Gyu Park
Summary: This study explores the effects of phase-change on the dynamics of cavitation bubbles over multiple cycles. A two-phase homogeneous mixture model combined with an interface-capturing method was used to simulate the bubble dynamics, taking into account compressibility, heat transfer, condensation, and evaporation.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Mechanics
Van-Tu Nguyen, Thanh-Hoang Phan, Trong-Nguyen Duy, Dong-Hyun Kim, Warn-Gyu Park
Summary: This study investigated the dynamic behavior of bubble collapses near walls and a free surface using numerical simulation, validating the results with experiments and providing important references for exploring phenomena related to bubble collapse.
INTERNATIONAL JOURNAL OF MULTIPHASE FLOW
(2022)
Article
Engineering, Marine
Van-Tu Nguyen, Warn-Gyu Park
Summary: In this study, the thermodynamic behavior and supercavitating flow around high-subsonic to supersonic speed projectiles were analyzed using numerical methods. The mathematical model, based on conservation laws, was solved on a body-fitted grid. The results showed that increasing the stream velocity significantly raised the temperature around the stagnation point, potentially damaging the projectile's steel encasing.
Article
Mathematics, Applied
Trong-Nguyen Duy, Van-Tu Nguyen, Thanh-Hoang Phan, Dong-Hyun Kim, Warn-Gyu Park
Summary: This paper presents a free surface flow solver based on an improved coupling method for practical, highly nonlinear, and complex free surface flows. The solver is validated with practical engineering applications, demonstrating its capability and potential for further applications.
COMPUTERS & MATHEMATICS WITH APPLICATIONS
(2022)
Article
Mechanics
Trong-Nguyen Duy, Van-Tu Nguyen, Warn-Gyu Park
Summary: In this study, numerical simulations were used to investigate the formation of bubbles by gas injection through an orifice in a stagnant liquid column and the flow field surrounding the bubbles after detachment under various flow conditions. The results indicated that the orifice radius and gas volume flow rate could predict the detachment time of bubbles and had a notable influence on the detached volume of bubbles. Additionally, the gas injection flow rate significantly affected the pressure field surrounding the bubbles after detachment, providing useful insights for studying bubbling flows and optimizing small-scale systems.
EUROPEAN JOURNAL OF MECHANICS B-FLUIDS
(2022)
Article
Thermodynamics
Trong-Nguyen Duy, Van-Tu Nguyen, Thanh-Hoang Phan, Hyun-Sung Hwang, Warn-Gyu Park
Summary: In this study, the dynamics of ventilated hot gas in underwater vehicles were investigated through numerical simulations. The effects of ventilated temperatures on the cavitating flow were examined, providing valuable insights for the design and optimization of the ventilation system in underwater vehicles.
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
(2022)
Article
Engineering, Marine
Van-Tu Nguyen, Thanh-Hoang Phan, Trong-Nguyen Duy, Warn-Gyu Park
Summary: This study investigates the flow behavior of cavitation around projectiles moving beneath a free surface using a numerical method. The findings are significant for the design and control of submerged vehicles and projectiles operating in such flow fields.
Article
Mechanics
Quang-Thai Nguyen, Van-Tu Nguyen, Thanh-Hoang Phan, Trong-Nguyen Duy, Seong-Ho Park, Warn-Gyu Park
Summary: This paper numerically studies the dynamics of initially spherical bubble collapse near an oscillating rigid wall. Numerical simulations were conducted using a compressible two-phase flow model and the volume of fluid (VOF) interphase-sharpening technique on a general curvilinear moving grid. The effects of the oscillating wall on bubble collapse were investigated, and the interface deformation, jetting behavior, bubble collapse time, and bubble migration were determined.
Review
Physics, Fluids & Plasmas
Van-Tu Nguyen, Warn-Gyu Park
Summary: This review paper summarizes recent advancements in time-marching schemes for solving Navier-Stokes equations in multiphase flow simulations, focusing on dual-time stepping, local preconditioning, and artificial compressibility methods. These methods have been proven effective in achieving high time accuracy and converting incompressible NS equations into a hyperbolic form for solution convergence acceleration and simulation of compressible flows at all Mach numbers. The continuing growth of literature on these methods provides deeper understanding of underlying physical processes and supports technological advancements. The paper also emphasizes the imposition of dual-time stepping on both incompressible and compressible NS equations. It provides an updated overview for the CFD community to develop methods and select the most suitable two-phase flow solver for their respective applications.
Article
Engineering, Marine
Trong-Nguyen Duy, Thanh-Hoang Phan, Quang-Thai Nguyen, Seong-Ho Park, Warn-Gyu Park
Summary: This study investigates bubble dynamics with highly nonlinear interactions between an oscillating bubble and gas-liquid interface in the vicinity of a rigid wall with a gas-entrapping hole through numerical simulations. The simulations show that the gas entrapped inside the hole significantly affects the formation and redirection of the liquid jet, as well as the dynamics of the cavitation bubble.
Article
Mechanics
Van-Tu Nguyen, Thanh-Hoang Phan, Warn-Gyu Park
Summary: This study validates the applicability of the fully conservative compressible multiphase flow model in simulating the collapse of cavitation bubbles. The numerical method effectively captures the strong shocks induced by the collapse, and the simulation results show a high level of agreement with experimental data. The study provides valuable insight into the complex behavior of cavitation bubbles in a free field.
Article
Computer Science, Interdisciplinary Applications
Jin Bao, Zhaoli Guo
Summary: At the equilibrium state of a two-phase fluid system, the chemical potential is constant and the velocity is zero. However, it is challenging to capture this equilibrium state accurately in numerical simulations, resulting in inconsistent thermodynamic interfacial properties and spurious velocities. Therefore, numerical schemes with well-balanced properties are preferred for simulating two-phase flows.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Brian C. Vermeire
Summary: This study presents a framework for implicit large eddy simulation (ILES) of incompressible flows by combining the entropically damped artificial compressibility (EDAC) method with the flux reconstruction (FR) approach. Experimental results demonstrate that the method is accurate and stable for low-order solutions, while higher-order solutions exhibit significantly higher accuracy and lower divergence error compared to reference direct numerical simulation.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Mijian Li, Rui Wang, Xinyu Guo, Xinyu Liu, Lianzhou Wang
Summary: In this study, the flow mechanisms around wall-mounted structures were investigated using Large Eddy Simulation (LES). The impact of inflow turbulence on the flow physics, dynamic response, and hydrodynamic performance was explored. The results revealed strong interference between velocity fluctuations and the wake past the cylinder, as well as significant convection effects in the far wake region.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Donatella Passiatore, Luca Sciacovelli, Paola Cinnella, Giuseppe Pascazio
Summary: A high-order shock-capturing central finite-difference scheme is evaluated for numerical simulations of hyper-sonic high-enthalpy flows out of thermochemical equilibrium. The scheme utilizes a tenth-order accurate central-difference approximation of inviscid fluxes, along with high-order artificial dissipation and shock-capturing terms. The proposed approach demonstrates accuracy and robustness for a variety of thermochemical non-equilibrium configurations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Philipp Bahavar, Claus Wagner
Summary: Condensation is an important aspect in flow applications, and simulating the gas phase and tracking the deposition rates of condensate droplets can capture the effects of surface droplets on the flow while reducing computational costs.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Andras Szabo, Gyorgy Paal
Summary: This paper introduces an efficient calculation method, the parabolized stability equations (PSE), for solving stability equations. By calculating LU factorization once in each marching step, the time spent on solving linear systems of equations can be significantly reduced. Numerical experiments demonstrate the effectiveness of this method in reducing the solution time for linear equations, and its applicability to similar problems.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
A. Khalifa, M. Breuer
Summary: This study evaluates a recently developed data-driven model for collision-induced agglomerate breakup in high mass loading flows. The model uses artificial neural networks to predict the post-collision behavior of agglomerates, reducing computational costs compared to coupled CFD-DEM simulations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Chunmei Du, Maojun Li
Summary: This paper considers the bilayer shallow water wave equations in one-dimensional space and presents an invariant domain preserving DG method to avoid Kelvin-Helmholtz instability.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Jean-Michel Tucny, Mihir Durve, Andrea Montessori, Sauro Succi
Summary: The prediction of non-equilibrium transport phenomena in disordered media is a challenging problem for conventional numerical methods. Physics-informed neural networks (PINNs) show potential for solving this inverse problem. In this study, PINNs were used to successfully predict the velocity field of rarefied gas flow, and AdamW was found to be the best optimizer.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Min Gao, Pascal Mossier, Claus-Dieter Munz
Summary: In recent decades, the arbitrary Lagrangian-Eulerian (ALE) approach has gained popularity in dealing with fluid flows with moving boundaries. This paper presents a novel algorithm that combines the ALE finite volume (FV) and ALE discontinuous Galerkin (DG) methods into a stable and efficient hybrid approach. The main challenge of this mixed ALE FV and ALE DG method is reducing the inconsistency between the two discretizations. The proposed algorithm is implemented into a loosely-coupled fluid-structure interaction (FSI) framework and is demonstrated through various benchmark test cases and complex scenarios.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Dawid Strzelczyk, Maciej Matyka
Summary: In this study, the numerical convergence of the Meshless Lattice Boltzmann Method (MLBM) is investigated through three benchmark tests. The results are compared to the standard Lattice Boltzmann Method (LBM) and the analytical solution of the Navier-Stokes equation. It is found that MLBM outperforms LBM in terms of error value for the same number of nodes discretizing the domain.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Kanishka Bhattacharya, Tapan Jana, Amit Shaw, L. S. Ramachandra, Vishal Mehra
Summary: In this work, an adaptive algorithm is developed to address the issue of tensile instability in Smoothed Particle Hydrodynamics (SPH) by adjusting the shape of the kernel function to satisfy stability conditions. The effectiveness of the algorithm is demonstrated through dispersion analysis and fluid dynamics simulations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Luis Laguarda, Stefan Hickel
Summary: We propose several enhancements to improve the accuracy and performance of the digital filter turbulent inflow generation technique, such as introducing a more realistic correlation function and varying target length scales. Additionally, we suggest generating inflow data in parallel at a prescribed time interval to improve computational performance. Based on the results of large-eddy simulations, these enhancements have shown to be beneficial. Suppressing streamwise velocity fluctuations at the inflow leads to the fastest relaxation of pressure fluctuations. However, this approach increases the adaptation length, which can be shortened by artificially increasing the wall-normal Reynolds stresses.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Constantin Zenz, Michele Buttazzoni, Tobias Florian, Katherine Elizabeth Crespo Armijos, Rodrigo Gomez Vazquez, Gerhard Liedl, Andreas Otto
Summary: A new model for compressible multiphase flows involving sharp interfaces and phase change is presented, with a focus on the treatment of compressibility and phase change in the multiphase fluid flow model. The model's accuracy and suitability are demonstrated through comparisons with experimental observations.
COMPUTERS & FLUIDS
(2024)
Article
Computer Science, Interdisciplinary Applications
Joseph O'Connor, Sylvain Laizet, Andrew Wynn, Wouter Edeling, Peter V. Coveney
Summary: This article aims to apply uncertainty quantification and sensitivity analysis to the direct numerical simulation (DNS) of low Reynolds number wall-bounded turbulent channel flow. By using a highly scalable DNS framework and UQ techniques, the study evaluates the influence of different numerical parameters on the simulation results without explicitly modifying the code. The findings provide guidance for numerical simulations of wall-bounded turbulent flows.
COMPUTERS & FLUIDS
(2024)
