Bound-preserving remapping of staggered quantities for multi-material ALE methods

2017 ◽  
Author(s):  
Milan Kucharik ◽  
Mikhail Shashkov
Keyword(s):  
Ale Methods

scholarly journals A linear-elasticity-based mesh moving method with no cycle-to-cycle accumulated distortion

2021 ◽  
Author(s):  
Patrícia Tonon ◽  
Rodolfo André Kuche Sanches ◽  
Kenji Takizawa ◽  
Tayfun E. Tezduyar
Keyword(s):  
Linear Elasticity ◽  
Solid Surfaces ◽  
Moving Mesh ◽  
Test Case ◽  
Half Cycle ◽  
Arbitrary Lagrangian Eulerian ◽  
Interface Motion ◽  
Mesh Motion ◽  
Ale Methods ◽  
Moving Mesh Methods

AbstractGood mesh moving methods are always part of what makes moving-mesh methods good in computation of flow problems with moving boundaries and interfaces, including fluid–structure interaction. Moving-mesh methods, such as the space–time (ST) and arbitrary Lagrangian–Eulerian (ALE) methods, enable mesh-resolution control near solid surfaces and thus high-resolution representation of the boundary layers. Mesh moving based on linear elasticity and mesh-Jacobian-based stiffening (MJBS) has been in use with the ST and ALE methods since 1992. In the MJBS, the objective is to stiffen the smaller elements, which are typically placed near solid surfaces, more than the larger ones, and this is accomplished by altering the way we account for the Jacobian of the transformation from the element domain to the physical domain. In computing the mesh motion between time levels $$t_n$$ t n and $$t_{n+1}$$ t n + 1 with the linear-elasticity equations, the most common option is to compute the displacement from the configuration at $$t_n$$ t n . While this option works well for most problems, because the method is path-dependent, it involves cycle-to-cycle accumulated mesh distortion. The back-cycle-based mesh moving (BCBMM) method, introduced recently with two versions, can remedy that. In the BCBMM, there is no cycle-to-cycle accumulated distortion. In this article, for the first time, we present mesh moving test computations with the BCBMM. We also introduce a version we call “half-cycle-based mesh moving” (HCBMM) method, and that is for computations where the boundary or interface motion in the second half of the cycle consists of just reversing the steps in the first half and we want the mesh to behave the same way. We present detailed 2D and 3D test computations with finite element meshes, using as the test case the mesh motion associated with wing pitching. The computations show that all versions of the BCBMM perform well, with no cycle-to-cycle accumulated distortion, and with the HCBMM, as the wing in the second half of the cycle just reverses its motion steps in the first half, the mesh behaves the same way.

scholarly journals Transient Response of a Projectile in Gun Launch Simulation Using Lagrangian and Ale Methods

2010 ◽  
Vol 4 (2) ◽  
pp. 151-173
Author(s):  
Ala Tabiei ◽  
Mostafiz R. Chowdhury ◽  
N. Aquelet ◽  
M. Souli
Keyword(s):  
Transient Response ◽  
Ale Methods

Validation of an Improved Contact Method for Multi-Material Eulerian Hydrocodes in Three-Dimensions

2019 ◽  
Author(s):  
Kenneth C. Walls ◽  
David L. Littlefield
Keyword(s):  
Finite Element ◽  
Large Deformations ◽  
Three Dimensions ◽  
Contact Method ◽  
Arbitrary Lagrangian Eulerian ◽  
Aspect Ratios ◽  
Ale Methods ◽  
Lagrangian Finite Element ◽  
Multiple Materials ◽  
Natural Description

Abstract Realistic and accurate modeling of contact for problems involving large deformations and severe distortions presents a host of computational challenges. Due to their natural description of surfaces, Lagrangian finite element methods are traditionally used for problems involving sliding contact. However, problems such as those involving ballistic penetrations, blast-structure interactions, and vehicular crash dynamics, can result in elements developing large aspect ratios, twisting, or even inverting. For this reason, Eulerian, and by extension Arbitrary Lagrangian-Eulerian (ALE), methods have become popular. However, additional complexities arise when these methods permit multiple materials to occupy a single finite element.

Multi-Material ALE methods in unstructured grids

2000 ◽  
Vol 187 (3-4) ◽  
pp. 591-619 ◽  
Author(s):  
James S. Peery ◽  
Daniel E. Carroll
Keyword(s):  
Unstructured Grids ◽  
Ale Methods

scholarly journals 3D FEM Simulation of the Flow Forming Process Using Lagrangian and ALE Methods

2007 ◽  
Author(s):  
Marie Houillon ◽  
Elisabeth Massoni ◽  
Eric Ramel ◽  
Roland Logé
Keyword(s):  
Fem Simulation ◽  
Forming Process ◽  
3D Fem ◽  
Flow Forming ◽  
Ale Methods

Numerical Investigation of Flow Interference Effects in Fixed and Vibrating Tandem Square Columns Using Hybrid RANS-LES Models

2015 ◽  
Author(s):  
Harish Gopalan ◽  
Dominic Denver John Chandar ◽  
Narasimha Rao Pillamarri ◽  
Guan Mengzhao ◽  
Rajeev K. Jaiman ◽  
...  
Keyword(s):  
Solid Wall ◽  
Computational Cost ◽  
Reynolds Numbers ◽  
Navier Stokes ◽  
Arbitrary Lagrangian Eulerian ◽  
High Reynolds Numbers ◽  
Flow Past ◽  
Ale Methods ◽  
High Reynolds ◽  
Flow Interference

Investigation of flow past tandem and side-by-side circular and square columns is of interest in offshore engineering. Flow past fixed and vibrating circular columns has received a lot of focus in the literature. However, the studies focused on square columns, especially at high Reynolds numbers are very limited due to the computational cost of large eddy simulation (LES). Unsteady Reynolds-averaged Navier-Stokes (URANS) methods are limited by their accuracy, especially for tandem columns in the wake interference regime (spacing to diameter ratio: L=D ∼ 3:0). Hybrid URANS-LES models (URANS near the solid-wall and LES away from the wall) can overcome the drawbacks of the traditional URANS methods and can provide a reasonable prediction of the flow physics at a fraction of the cost of LES without significantly sacrificing numerical accuracy. Arbitrary Lagrangian-Eulerian (ALE) methods fails when vibrating tandem bodies are in close proximity to each other or vibrate at high reduced velocities. Remeshing the domain can be expensive, especially at high Reynolds numbers (Re). Alternate strategies are necessary to efficiently simulation this problems. This study proposes the use of a non-linear URANS-LES model, coupled with an overset mesh method (for vibrating columns), for studying flow past tandem square columns. Simulations are performed at sub-critical Re to match the experimental Re. The initial results are encouraging for further investigation of fixed and vibrating tandem square column flow interference at high Reynolds numbers.

Multiphysics Study of Structural Impact to Fluidic Media

2011 ◽  
Vol 673 ◽  
pp. 1-10 ◽  
Author(s):  
Matej Vesenjak ◽  
Zoran Ren ◽  
Mojtaba Moatamedi
Keyword(s):  
Impact Loading ◽  
Numerical Study ◽  
Fluid Structure Interaction ◽  
Water Impact ◽  
Fluid Structure ◽  
Structure Interaction ◽  
Particle Hydrodynamics ◽  
Ale Methods ◽  
Smoothed Particle ◽  
Space Capsule

The paper presents a fluid structure interaction based numerical study of impact loading for a hemispherical structure upon water and a space capsule water landing. The study has a strong relevance in the determination of the crashworthiness of aerospace structures upon water impact loading. Finite element based numerical techniques have been used for the analysis of the underlying transient dynamic and fluid-structure interaction. Smoothed Particle Hydrodynamics (SPH) and Arbitrary Lagrange-Eulerian (ALE) methods have been used to simulate the behaviour of the fluid (water) under impact conditions. The accelerations and velocities of the impacting objects have been validated with by experimental measurements and analytical results. Numerical analyses showed a strong potential for the use of developed computational fluid structure interaction models for analyses of water impact loading related problems.

scholarly journals Design of a Nonhydrostatic Atmospheric Model Based on a Generalized Vertical Coordinate

2009 ◽  
Vol 137 (7) ◽  
pp. 2305-2330 ◽  
Author(s):  
Michael D. Toy ◽  
David A. Randall
Keyword(s):  
Atmospheric Model ◽  
Static Stability ◽  
Vertical Coordinate ◽  
Adiabatic Flow ◽  
Pressure Drag ◽  
Model Based ◽  
Ale Methods ◽  
Coordinate Model ◽  
Atmospheric Motion ◽  
Limiting Case

The isentropic system of equations has particular advantages in the numerical modeling of weather and climate. These include the elimination of the vertical velocity in adiabatic flow, which simplifies the motion to a two-dimensional problem and greatly reduces the numerical errors associated with vertical advection. The mechanism for the vertical transfer of horizontal momentum is simply the pressure drag acting on isentropic coordinate surfaces under frictionless, adiabatic conditions. In addition, vertical resolution is enhanced in regions of high static stability, which leads to better resolution of features such as the tropopause. Negative static stability and isentropic overturning frequently occur in finescale atmospheric motion. This presents a challenge to nonhydrostatic modeling with the isentropic vertical coordinate. This paper presents a new nonhydrostatic atmospheric model based on a generalized vertical coordinate. The coordinate is specified in a manner similar to that of Konor and Arakawa, but “arbitrary Eulerian–Lagrangian” (ALE) methods are used to maintain coordinate monotonicity in regions of negative static stability and to return the coordinate surfaces to their isentropic “targets” in statically stable regions. The model is mass conserving and implements a vertical differencing scheme that satisfies two additional integral constraints for the limiting case of z coordinates. The hybrid vertical coordinate model is tested with mountain-wave experiments including a downslope windstorm with breaking gravity waves. The results show that the advantages of the isentropic coordinate are realized in the model with regard to vertical tracer and momentum transport. Also, the isentropic overturning associated with the wave breaking is successfully handled by the coordinate formulation.

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