scholarly journals Coupling with the Embedded Boundary Method in a Runge-Kutta Discontinuous-Galerkin Direct Ghost-Fluid Method (RKDG-DGFM) Framework for Fluid-Structure Interaction Simulations of Underwater Explosions

2021 ◽  
Vol 9 (12) ◽  
pp. 1375
Author(s):  
Nan Si ◽  
Zhaokuan Lu ◽  
Alan Brown
Keyword(s):  
Discontinuous Galerkin ◽  
Fluid Structure Interaction ◽  
Structural Deformation ◽  
Modeling Framework ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Boundary Method ◽  
Embedded Boundary ◽  
Runge Kutta ◽  
Embedded Boundary Method

Solution of near-field underwater explosion (UNDEX) problems frequently require the modeling of two-way coupled fluid-structure interaction (FSI). This paper describes the addition of an embedded boundary method to an UNDEX modeling framework for multiphase, compressible and inviscid fluid using the combined algorithms of Runge-Kutta, discontinuous-Galerkin, level-set and direct ghost-fluid methods. A computational fluid dynamics (CFD) solver based on these algorithms has been developed as described in previous work. A fluid-structure coupling approach was required to perform FSI simulation interfacing with an external structural mechanics solver. Large structural deformation and possible rupture and cracking characterize the FSI phenomenon in an UNDEX, so the embedded boundary method (EBM) is more appealing for this application in comparison to dynamic mesh methods such as the arbitrary Lagrangian-Eulerian (ALE) method to enable the fluid-structure coupling algorithm in the fluid. Its limitation requiring a closed interface that is fully submerged in the fluid domain is relaxed by an adjustment described in this paper so that its applicability is extended. Two methods of implementing the fluid-structure wall boundary condition are also compared. The first solves a local 1D fluid-structure Riemann problem at each intersecting point between the wetted elements and fluid mesh. In this method, iterations are required when the Tait equation of state is utilized. A second method that does not require the Riemann solution and iterations is also implemented and the results are compared.

Fast and Accurate Simulation of Strongly Coupled Fluid-Structure Interaction Using a Direct Forcing Immersed Boundary Method

2011 ◽  
Author(s):  
Jianming Yang ◽  
Frederick Stern
Keyword(s):  
Immersed Boundary Method ◽  
Fluid Structure Interaction ◽  
Immersed Boundary ◽  
Coupling Scheme ◽  
Fluid Structure ◽  
Strongly Coupled ◽  
Structure Interaction ◽  
Boundary Method ◽  
Embedded Boundary ◽  
Direct Forcing

In this paper, a direct forcing immersed boundary method is presented for the simple and efficient simulation of strongly coupled fluid-structure interaction. The previous formulation by Yang and Balaras (An embedded-boundary formulation for large-eddy simulation of turbulent flows interacting with moving boundaries, J. Comput. Phys. 215 (2006) 12–40) is greatly simplified without sacrificing the overall accuracy. The fluid-structure coupling scheme of Yang et al. (A strongly-coupled, embedded-boundary method for fluid-structure interactions of elastically mounted rigid bodies, J. Fluids Struct. 24 (2008) 167–182) is also significantly expedited without altering the strong coupling property. Several cases are examined and compared with the results from the previous formulations to demonstrate the accuracy, simplicity and efficiency of the new method.

Dynamic Analysis of the Joined-Wing Configuration in High-Altitude Long-Endurance Aircraft Using Fluid-Structure Interaction Model

2007 ◽  
Author(s):  
Prabu Ganesh Ravindren ◽  
Kirti Ghia ◽  
Urmila Ghia
Keyword(s):  
Finite Element ◽  
High Altitude ◽  
Fluid Structure Interaction ◽  
Structural Deformation ◽  
Time Step ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Finite Element Software ◽  
Joined Wing ◽  
Long Endurance

Recent studies of the joined-wing configuration of the High Altitude Long Endurance (HALE) aircraft have been performed by analyzing the aerodynamic and structural behaviors separately. In the present work, a fluid-structure interaction (FSI) analysis is performed, where the fluid pressure on the wing, and the corresponding non-linear structural deformation, are analyzed simultaneously using a finite-element matrix which couples both fluid and structural solution vectors. An unsteady, viscous flow past the high-aspect ratio wing causes it to undergo large deflections, thus changing the domain shape at each time step. The finite element software ANSYS 11.0 is used for the structural analysis and CFX 11.0 is used for the fluid analysis. The structural mesh of the semi-monocoque joined-wing consists of finite elements to model the skin panel, ribs and spars. Appropriate mass and stress distributions are applied across the joined-wing structure [Kaloyanova et al. (2005)], which has been optimized in order to reduce global and local buckling. The fluid region is meshed with very high mesh density at the fluid-structure interface and where flow separation is predicted across the joint of the wing. The FSI module uses a sequentially-coupled finite element equation, where the main coupling matrix utilizes the direction of the normal vector defined for each pair of coincident fluid and structural element faces at the interface [ANSYS 11.0 Documentation]. The k-omega turbulence model captures the fine-scale turbulence effects in the flow. An angle of attack of 12°, at a Mach number of 0.6 [Rangarajan et al. (2003)], is used in the simulation. A 1-way FSI analysis has been performed to verify the proper transfer of loads across the fluid-structure interface. The CFX pressure results on the wing were transferred across the comparatively coarser mesh on the structural surface. A maximum deflection of 16 ft is found at the wing tip with a calculated lift coefficient of 1.35. The results have been compared with the previous study and have proven to be highly accurate. This will be taken as the first step for the 2-way simulation. The effect of a coupled 2-way FSI analysis on the HALE aircraft joined wing configuration will be shown. The structural deformation history will be presented, showing the displacement of the joined-wing, along the wing span over a period of aerodynamic loading. The fluid-structure interface meshing and the convergence at each time step, based on the quantities transferred across the interface will also be discussed.

Fluid–Structure Interaction Study and Flowrate Prediction Past a Flexible Membrane Using Immersed Boundary Method and Artificial Neural Network Techniques

2020 ◽  
Vol 142 (5) ◽  
Author(s):  
Mithun Kanchan ◽  
Ranjith Maniyeri
Keyword(s):  
Neural Network ◽  
Artificial Neural Network ◽  
Immersed Boundary Method ◽  
Fluid Structure Interaction ◽  
Immersed Boundary ◽  
Flexible Membrane ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Boundary Method ◽  
Artificial Neural

Abstract Many microfluidics-based applications involve fluid–structure interaction (FSI) of flexible membranes. Thin flexible membranes are now being widely used for mixing enhancement, particle segregation, flowrate control, drug delivery, etc. The FSI simulations related to these applications are challenging to numerically implement. In this direction, techniques like immersed boundary method (IBM) have been successful. In this study, two-dimensional numerical simulation of flexible membrane fixed at two end points in a rectangular channel subjected to uniform fluid flow is carried out at low Reynolds number using a finite volume based IBM. A staggered Cartesian grid system is used and SIMPLE algorithm is used to solve the governing continuity and Navier–Stokes equations. The developed model is validated using the previous research work and numerical simulations are carried out for different parametric test cases. Different membrane mode shapes are observed due to the complex interplay between the hydrodynamics and structural elastic forces. Since the membrane undergoes deformation with respect to inlet fluid conditions, a variation in flowrate past the flexible structure is confirmed. It is found that, by changing the membrane length, bending rigidity, and its initial position in the channel, flowrate can be controlled. Also, for membranes that are placed at the channel midplane undergoing self-excited oscillations, there exists a critical dimensionless membrane length condition L ≥ 1.0 that governs this behavior. Finally, an artificial neural network (ANN) model is developed that successfully predicts flowrate in the channel for different membrane parameters.

Sign in / Sign up

Export Citation Format

Share Document