Immersed Boundary Methods - Science topic

Evidence shows that gorgonians are more resistant to ocean acidification and rising temperatures than hard corals and are vital to reef health and the reestablishment of disrupted coral reef communities. Gorgonian coral's resilience and its diversity of morphology and environment make it well‐suited as a model organism for bioinspired design applie...

The flow-induced oscillation of an S-shaped buckled flexible filament was explored using the penalty immersed boundary method. As the length and bending rigidity of the filament were varied, three distinct modes emerged: the equilibrium mode, streamwise oscillation (SO) mode and transverse oscillation (TO) mode. A transition region between the SO a...

The effects of the twisting-induced variation in the effective angle of attack, α e f f , on the aerodynamics and the leading edge vortex (LEV) of a flapping wing are investigated using the lattice Boltzmann method (LBM) and an immersed boundary method (IBM). If the wing is rigid during the flapping flight, α e f f of the outer portion of the wing...

The vortex-induced vibration of a circular cylinder and two inline circular cylinders near a plane wall at a Reynolds number of 150 is numerically investigated by using a self-developed immersed boundary method called the local domain-free discretization (DFD) method. The cylinders are elastically mounted with a mass ratio of and a 0 damping ratio...

The Immersed Boundary (IB) method, integrated with the large-eddy simulation technique, has been developed further to model neutrally stratified atmospheric flows over complex terrains. This advancement involves a logarithmic IB reconstruction scheme that accounts for surface parameterization of momentum flux and enhances the subgrid-scale viscosit...

The simulation of wave-structure interaction problems is still hard work, especially when the structure is complex and violent phenomena including wave breaking and slamming occur. In this paper, a simple model for simulating violent wave-structure interactions is developed. The decoupling of velocity and pressure is achieved by the fractional step...

Adaptive mesh refinement (AMR) technology and high-order methods are important means to improve the quality of simulation results and have been hotspots in the computational fluid dynamics community. In this paper, high-order discontinuous Galerkin (DG) and direct DG (DDG) finite element methods are developed based on a parallel adaptive Cartesian...

This work presents a numerical method for modeling fluid–structure–acoustics interaction (FSAI) problems involving large deformation. The method incorporates an immersed boundary method and a regularized lattice Boltzmann method (LBM) where a multi-block technique and a nonreflecting boundary condition are implemented. The von Neumann analysis is c...

In this paper, we examine the coupling between odor dynamics and vortex dynamics around undulating bodies, with a focus on bio-inspired propulsion mechanisms. Utilizing computational fluid dynamics simulations with an in-house immersed boundary method solver, we investigate how different waveform patterns, specifically carangiform and anguilliform,...

Rigid–flexible coupling fluid–structure interaction systems are expected to be future solutions for reducing energy lost in water. The dynamics of these systems is usually investigated via numerical simulations. However, in existing numerical works there is no accurate algorithm for the initialization of the flexible filament, which ensures both th...

A new immersed boundary method is proposed for the numerical simulation of the melting of solid particles in its own liquid at a high temperature. The main feature of the new method is the use of the modified direct-forcing immersed boundary method for the solution of the flow field and the sharp-interface immersed boundary method for the temperatu...

It has been well known that the shear layers behind a prism at subcritical Reynolds number (Re) remain persistently stable. However, potential response of an elastically mounted non-circular prism at subcritical Re is still open. In this study, we numerically investigate the flow-induced vibrations of an equilateral triangular prism at subcritical...

We present the IAMReX (incompressible flow with adaptive mesh refinement for the eXascale), an adaptive and parallel solver for particle-resolved simulations on the multi-level grid. The fluid equations are solved using a finite-volume scheme on the block-structured semi-staggered grids with both subcycling and non-subcycling methods. The particle-...

This paper presents a hybrid numerical method for simulating the boiling heat transfer in particle-laden fluids. The coupled volume of fluid and level set method, immersed boundary method, and discrete element method are integrated for gas–liquid flow, fluid–solid interaction, and the collision between particles. The energy jump model is adopted to...

Wave-assisted propulsion (WAP) systems directly convert wave energy into thrust using elastically mounted hydrofoils. The wave conditions as well as the design of the hydrofoil drive the fluid–structure interaction of the hydrofoil and, consequently, its performance. We employ simulations using a sharp-interface immersed boundary method to examine...

This study presents a novel approach that integrates explicit non-equilibrium wall modeling with the diffused-interface immersed boundary method (IBM) and couples it with high-order compact finite difference method (FDM). This framework efficiently models high Reynolds number turbulent flows over obstacles. The major contributions of this study are...

Predicting droplet transport in the atmosphere is a major issue for a large number of dispersion problems such as spray cooling systems in streets, urban lawn sprinklers [Milesi et al., “Interferometric laser imaging for respiratory droplets sizing,” Environ. Manage. 36, 426–438 (2005)], and dispersion of virus such as COVID or from a terrorist att...

To elucidate complex flow phenomena in the solid rocket motor (SRM), it is beneficial to reduce development costs by employing computational fluid dynamics simulation, as conducting full-scale model experiments for SRM is expensive. This study focuses on numerically simulating the internal flow in the cylinder simulating the SRM geometry using the...

Given the advantages of flexible wave energy converters (FlexWECs), such as deformation-led energy harnessing and structural loading compliance, there has been a significant interest in FlexWECs in both academia and industries. To simulate the FlexWEC interaction with ocean surface waves, a 3D computational fluid-structure interaction approach is d...

This work presents a comprehensive framework for enhanced diffusion modeling in fluid-structure interactions by combining the Immersed Boundary Method (IBM) with stochastic trajectories and high-order spectral boundary conditions. Using semi-Lagrangian schemes, this approach captures complex diffusion dynamics at moving interfaces, integrating prob...

We develop a computational method for modeling electrostatic interactions of arbitrarily shaped, polarizable objects on colloidal length scales, including colloids/nanoparticles, polymers, and surfactants, dispersed in explicit ion electrolytes and nonionic solvents. Our method computes the nonuniform polarization charge distribution induced in a c...

The peculiar migration and rotational dynamics of non-spherical particles in non-Newtonian flows stem from the interplay between fluid rheology and fluid inertial effects. In this paper, the cross-flow migration of a neutrally buoyant oblate spheroid (aspect ratio $AR = 0.5$ ) immersed in the elasto-inertial duct flow is investigated by particle-re...

An improved implicit direct-forcing immersed boundary method (DF-IBM) is presented for simulating incompressible flows around complex rigid structures undergoing arbitrary motion. The current approach harnesses the pressure implicit with splitting of operators algorithm to handle the fluid–solid system's dual constraints in a segregated manner. As...

Two-dimensional (2D) and three-dimensional (3D) numerical models are commonly employed to investigate the kinematic and hydrodynamic characteristics of fish maneuvers. In this study, we captured the posture characteristics of zebrafish during C-type maneuvers using high-speed photography and constructed a midline curvature model via the tandem prin...

Highly biosimilar manta ray morphological and kinematic models are first established, followed by a numerical study of the hydrodynamic characteristics of two manta rays swimming in tandem under the same/reverse phase-difference conditions based on the immersed boundary method. The results show that, compared to single swimming, under the same/reve...

Immersed boundary method (IBM) can easily distinguish fluid and solid regions in the computational region, thereby the workload of complex grid generation can be reduced. To accurately characterize the solid geometry, a large number of cells are required near the solid surface. The h-adaptive algorithm is adopted to reduce the requirement for the n...

In equipment within the aviation and marine industries, aerodynamic and hydrodynamic noises generated by the coupling effect between moving structures (such as equipment shells, landing gears, blades, etc.) and fluid media are ubiquitous. These noises significantly impact the noise levels of the equipment and its surrounding environment, posing thr...

This study presents a comprehensive numerical investigation into the nonlinear dynamics of Dipteran-inspired flapping flight systems at low Reynolds numbers, with the goal of advancing micro aerial vehicle (MAV) design. Using a forced Duffing oscillator model to represent the wing's structural dynamics and an in-house Navier–Stokes solver based on...

This article investigates the impact of atmospheric turbulence on wind farms in mountainous regions using Scale-Adaptive Large-Eddy Simulation (SALES) combined with the immersed boundary method. An array of 25 Gaussian hills was considered to mimic the mountainous terrain, and three cases were simulated: atmospheric boundary layer flow over complex...

To handle multiphase (i.e., gas–liquid–solid) flow problems, an algorithm coupling the CLSVOF/IB (coupled level set and volume of fluid/immersed boundary) method with adaptive mesh refinement (AMR) for simulating multiphase flows is proposed in this paper. First, in order to accurately predict the gas–liquid interface, intermediate, re-distancing,...

The sharp-interface immersed boundary method (IBM) reconstructs the flow locally to achieve the precise identification of solid boundaries and their consequential influences on the fluid dynamics. However, the computational accuracy and efficiency are notably impacted by the diverse interaction between the fluid's Euler grid and the solid's Lagrang...

An original Immersed Boundary Method for solving moving body flows is proposed. This method couples (i) a Lagrangian Volume‐of‐Solid description of the solid object avoiding conservation issues and (ii) a robust implicit volume penalty forcing embedded in a low‐Mach number projection method to account for the solid's impact on the fluid dynamics. A...

To understand fish swimming behavior in unsteady flows, this paper introduces the Kármán gait model to numerically investigate the hydrodynamics of fish-like swimming in an asymmetric vortex environment, specifically the P + S mode (a pair of vortices are shed from one side of the cylinder and a single vortex from the other side during one oscillat...

Up to now, researchers have been proposing various approaches to simulate two-phase flow in order to investigate physical phenomena such as wave breaking and wind-wave interaction. A fundamental aspect of simulating two-phase flow involves defining the physical characteristics of the two distinct fluids present; a technique known as interface const...

The flow boiling heat transfer in microchannels has been extensively used in engineering due to its high heat dissipation with a small temperature difference. This study employs a hybrid method to numerically investigate the effects of a flow-induced vibrating cylinder on enhancing the subcritical boiling heat transfer in microchannels. The hybrid...

We propose a robust, high-resolution prediction–correction projection immersed interface method (IIM) for solving the unsteady incompressible Navier–Stokes equations with traction boundary conditions, which arise from free surface flows driven by capillary, electric, and elastic forces. This method combines the advantages of traditional body-fitted...

While interactive simulations have been mostly limited to Computer Graphics applications, new generations of Graphics Processing Units (GPUs) allow the realization of industrial-grade interactive 3D physics simulations. By combining an immersed boundary method with efficient GPU-based MINRES and CG solvers using a GPU-based geometric multigrid prec...

We propose a novel solid-fluid interaction method for coupling elastic solids with impulse flow maps. Our key idea is to unify the representation of fluid and solid components as particle flow maps with different lengths and dynamics. The solid-fluid coupling is enabled by implementing two novel mechanisms: first, we developed an impulse-to-velocit...

We develop a deep reinforcement learning method for training a jellyfish-like swimmer to effectively track a moving target in a two-dimensional flow. This swimmer is a flexible object equipped with a muscle model based on torsional springs. We employ a deep Q-network (DQN) that takes the swimmer's geometry and dynamic parameters as inputs, and outp...

The direct-forcing immersed boundary method is one of the common methods for solving fluid-structure interaction problems. It can effectively handle complex solid geometries, including moving and deforming solids. However, three-dimensional complex flow simulation has the characteristics of large grid size and high time consumption, and using tradi...

We present a variant of the immersed boundary (IB) method that implements acoustic perturbation theory to model acoustically levitated fluid droplets. Instead of resolving sound waves numerically, our hybrid method solves acoustic scattering semi-analytically to obtain the corresponding time-averaged acoustic forces on the droplet. This framework a...

The settling of particles is related to many industrial processes and research fields. However, due to the complex particle–particle and particle–fluid interactions, the settling mechanism of particles in flowing fluids is not fully understood. This article conducts numerical research on the settling process of two particles with different diameter...

A novel passive flow-control method for shock-wave/turbulent boundary-layer interactions (STBLI) is investigated. The method relies on a structured roughness pattern constituted by streamwise-aligned ridges. Its effectiveness is assessed with wall-resolved large-eddy simulations of the interaction of a Mach 2 turbulent boundary layer flow with an o...

Fluid flows containing dispersed particles are abundant in both nature and industry. Simulating such flows, especially with high volumetric fractions of the dispersed solid phase, is challenging due to the complexity of solid-fluid and solid-solid interactions. In this paper, we introduce OpenHFDIB-DEM, an open-source software that couples computat...

The standard finite-difference time-domain (FDTD) wave solver employs a regular grid that approximates vocal tract boundaries in a stair-stepped manner, making it less effective for modeling complex and dynamic geometry. We present a novel 2D wave solver that integrates a unique immersed boundary method with FDTD, enabling precise approximation of...

Roughness of the surface underlying the atmospheric boundary layer causes departures of the near-surface scalar and momentum transport in comparison with aerodynamically smooth surfaces. Here, we investigate the effect of $56\times 56$ homogeneously distributed roughness elements on bulk properties of a turbulent Ekman flow. Direct numerical simula...

In the intricate realm of ocean-atmosphere dynamics, the sustained and stable operation of buoy observation systems under rough seas is crucial for ensuring marine resource security. This study employs a coupled Level-Set and Volume of Fluid (CLSVOF) method alongside the immersed boundary method. It investigates the physical processes of wind-wave...

The present work aims at studying the effect of veer, namely, the height-dependent lateral deflection of wind velocity due to Coriolis acceleration, on the coherent structures in the wake of the NREL 5-MW reference wind turbine using the sparsity-promoting dynamic mode decomposition (SP-DMD) method for the detection of dynamically-relevant flow str...

A numerical investigation is conducted on the propulsive performance and acoustic characteristics of two flapping foils in tandem at Re = 200 in uniform flow using the lattice Boltzmann method combined with the immersed boundary method. The effects of phase difference and horizontal spacing on hydrodynamics and acoustics are studied. The results in...

The stability of the immersed boundary (IB) method is a challenge in simulating fluid–structure interaction problems, where time step constraints are significantly stricter than in pure fluid simulations. We propose a novel unconditionally stable scheme for the immersed boundary finite element (IBFE) method. The structure is handled implicitly and...

uDALES is an open-source multi-physics microscale urban modelling tool, capable of performing large-eddy simulation (LES) of urban airflow, heat transfer, and pollutant dispersion. We present uDALES v2.0, which has two main new features: (1) an improved parallelisation that prepares the codebase for conducting exascale simulations and (2) a conserv...

The fine particle liquid–solid flow in porous media is involved in many industrial processes such as oil exploitation, geothermal reinjection and particle filtration. Understanding the migration characteristics of single fine particles in liquid–solid flow in porous media can provide micro-detailed explanations for the fine particle liquid–solid fl...

The microscale gas–particle interaction is the determining process for the macroscopic flow behaviors of gas–particle systems. Anisotropic Stefan flow is often manifested at the surface of the biomass particle when thermally decomposed. However, the influence of the anisotropic Stefan flow on the gas–particle interactions is not well understood. To...

The dynamics of a single flexible flag behind a semi-circular cylinder are investigated using vortex interaction study and dynamic mode decomposition (DMD). The problem is numerically solved using the immersed boundary method. For Reynolds number 300, by the variation of the streamwise gap between flag and bluff body ( Dx), five regions, each exhib...

This paper presents preliminary validation results of a new immersed boundary Wall-Modelled Large Eddy Simulation (WMLES) framework, Volcano ScaLES, for two automotive configurations as part of the 4 th Automotive CFD Prediction Workshop (AutoCFD 4): the Windsor Squareback body and the DrivAer Notchback model. For the Windsor body, grids of up to 3...

When planning a new wind farm, optimising the turbine layout to maximise power output is crucial. Traditional approaches based on analytical wake models often fail in complex terrain. In such areas, wake‐to‐wake interactions and terrain‐induced effects need to be taken into account via high‐fidelity optimisation. Building on our prior research on h...

The present work employs the immersed boundary method to perform direct simulations of flow-induced vibrations in a tandem cylinder at laminar flows, where only the upstream cylinder (UC) is allowed to vibrate. The primary focus is to elucidate the vibration response of the UC and the underlying hydrodynamic mechanisms when a fixed downstream cylin...

This work utilizes the Immersed Boundary Conformal Method (IBCM) to analyze Kirchhoff-Love and Reissner-Mindlin shell structures within an immersed domain framework. Immersed boundary methods involve embedding complex geometries within a background grid, which allows for great flexibility in modeling intricate shapes and features despite the simpli...