A Strongly Coupled Fluid Structure Interaction Solution for Transient Soft Elastohydrodynamic Lubrication Problems in Reciprocating Rod Seals Based on a Combined Moving Mesh Method

2015 ◽  
Vol 137 (4) ◽  
Author(s):  
Haiping Gao ◽  
Baoren Li ◽  
Xiaoyun Fu ◽  
Gang Yang
Keyword(s):  
Fluid Structure Interaction ◽  
Elastohydrodynamic Lubrication ◽  
Moving Mesh ◽  
Moving Mesh Method ◽  
Fluid Structure ◽  
Strongly Coupled ◽  
Structure Interaction ◽  
Fluid Field ◽  
Mesh Method ◽  
Rod Seals

Soft elastohydrodynamic lubrication (EHL) problems widely exist in hydraulic reciprocating rod seals and pose great challenges because of high nonlinearity and strong coupling effects, especially when the EHL problems are of high dimensions. In this paper, a strongly coupled fluid structure interaction (FSI) model is proposed to solve the transient soft EHL problems in U-cup hydraulic reciprocating rod seals. The Navier–Stokes equations, rather than the Reynolds equation, are employed to govern the whole fluid field in the soft EHL problems, with the nonlinearity of the solid taken into consideration. The governing equations of the fluid and solid fields are combined into one equation system and solved monolithically. To determine the displacements of nodes of the fluid field, a new moving mesh method based on the combination of the Laplace equation and the leader–follower methods is put forward. At last, the proposed FSI model runs successfully with the moving mesh method, and the boundaries of the hydrodynamic lubrication zones and the hydrostatic zones are formed automatically and change dynamically during the coupling process. The results are as follows: The soft EHL problems show typical characteristics, like the constriction effects of the lubricating films, and the law of dynamic development of the lubricating films and the fluid pressures is revealed. The minimum stroke lengths needed to generate complete lubricating films vary with the rod speeds and movement directions, so the design of the rod seals should be paid close attention to, in particular the rod seals of short stroke lengths. Furthermore, along with the dynamic development processes of the fluid pressures during the instroke of U-cup seals, the lubricating film humps expand and locate between the fluid pressure abrupt points and the outlet zones. After the U-cup seals reach the steady-states, the fluid abrupt points disappear and no changes of the film humps are observed. Theoretically, the proposed method can be popularized to solve similar soft EHL problems.

scholarly journals Mesh moving techniques in fluid-structure interaction: robustness, accumulated distortion and computational efficiency

2020 ◽  
Author(s):  
Alexander Shamanskiy ◽  
Bernd Simeon
Keyword(s):  
Fluid Structure Interaction ◽  
Continuation Methods ◽  
Moving Mesh Method ◽  
Important Ingredient ◽  
Fluid Structure ◽  
Harmonic Extension ◽  
Structure Interaction ◽  
Computational Mesh ◽  
Mesh Method ◽  
Moving Fluid

AbstractAn important ingredient of any moving-mesh method for fluid-structure interaction (FSI) problems is the mesh moving technique (MMT) used to adapt the computational mesh in the moving fluid domain. An ideal MMT is computationally inexpensive, can handle large mesh motions without inverting mesh elements and can sustain an FSI simulation for extensive periods of time without irreversibly distorting the mesh. Here we compare several commonly used MMTs which are based on the solution of elliptic partial differential equations, including harmonic extension, bi-harmonic extension and techniques based on the equations of linear elasticity. Moreover, we propose a novel MMT which utilizes ideas from continuation methods to efficiently solve the equations of nonlinear elasticity and proves to be robust even when the mesh undergoes extreme motions. In addition to that, we study how each MMT behaves when combined with the mesh-Jacobian-based stiffening. Finally, we evaluate the performance of different MMTs on a popular two-dimensional FSI benchmark reproduced by using an isogeometric partitioned solver with strong coupling.

Dynamics of a Free Heaving and Prescribed Pitching Hydrofoil in a Turbulent Flow, With a Fluid-Structure Interaction Approach

2018 ◽  
Author(s):  
P. Brousseau ◽  
M. Benaouicha ◽  
S. Guillou
Keyword(s):  
Fluid Structure Interaction ◽  
Vertical Displacement ◽  
Rotational Displacement ◽  
Fluid Structure ◽  
Strongly Coupled ◽  
Structure Interaction ◽  
Maximum Angle ◽  
High Maximum ◽  
Oscillating Foil ◽  
Interaction Approach

This paper deals with the dynamics of an oscillating foil, describing a free heaving (vertical displacement) and prescribed pitching (rotational displacement) movement which is computed from its position in two different ways. A fluid-structure interaction approach is chosen, as the physics of the flow and the structure are strongly coupled. The flow is unsteady, turbulent and incompressible. The pressure/velocity problem is solved using SIMPLEC scheme. First, the pitching movement is considered as a given continuous function of the hydrofoil heaving position. Second, the pitching motion is performed alternately at the end of each heave cycle. For each case, two maximum angles of attack and one heaving amplitudes are studied. Preliminary results showed that a high maximum angle of attack generates more lift hydrodynamics force, but also requires more energy to perform the rotation of pitch.

scholarly journals Study on Fluid-Structure Interaction of Flexible Membrane Structures in Wind-Induced Vibration

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Fangjin Sun ◽  
Donghan Zhu ◽  
Tiantian Liu ◽  
Daming Zhang
Keyword(s):  
Projection Method ◽  
Fluid Structure Interaction ◽  
Initial Pressure ◽  
Projection Methods ◽  
Accurate Solution ◽  
Membranous Structure ◽  
Fluid Structure ◽  
Strongly Coupled ◽  
Structure Interaction ◽  
Modified Projection Method

A strongly coupled monolithic method was previously proposed for the computation of wind-induced fluid-structure interaction of flexible membranous structures by the authors. How to obtain the accurate solution is a key issue for the strongly coupled monolithic method. Projection methods are among the commonly used methods for the coupled solution. In the work here, to impose initial pressure boundary conditions implicitly defined in the original momentum equations in classical projection methods when dealing with large-displacement of membranous structures, a modified factor is introduced in corrector step of classical projection methods and a new modified projection method is obtained. The solution procedures of the modified projection method aimed at strongly coupled monolithic equations are given, and the related equations are derived. The proposed method is applied to the computation of a two-dimensional fluid-structure interaction benchmark case and wind-induced fluid-structure interaction of a three-dimensional flexible membranous structure. The performance and efficiency of the modified projection method are evaluated. The results show that the modified projection methods are valid in the computation of wind-induced fluid-structure interaction of flexible membranous structures, with higher accuracy and efficiency compared with traditional methods. The modified value has little effects on the computation results whereas iteration times has significant effects. Computation accuracy can be improved greatly by increasing iteration times with less increase in computation time and little effects on stability with the modified projection method.

Numerical Investigation of Hydroelastic Response of a Three-Dimensional Deformable Hydrofoil

2020 ◽  
Author(s):  
Saeed Hosseinzadeh ◽  
Kristjan Tabri
Keyword(s):  
Pressure Coefficient ◽  
Fluid Structure Interaction ◽  
Three Dimensional ◽  
Leading Edge ◽  
Elastic Response ◽  
Fluid Structure ◽  
Strongly Coupled ◽  
Structure Interaction ◽  
Lift And Drag ◽  
Hydroelastic Response

The present study is concerned with the numerical simulation of Fluid-Structure Interaction (FSI) on a deformable three-dimensional hydrofoil in a turbulent flow. The aim of this work is to develop a strongly coupled two-way fluid-structure interaction methodology with a sufficiently high spatial accuracy to examine the effect of turbulent and cavitating flow on the hydroelastic response of a flexible hydrofoil. A 3-D cantilevered hydrofoil with two degrees-of-freedom is considered to simulate the plunging and pitching motion at the foil tip due to bending and twisting deformation. The defined problem is numerically investigated by coupled Finite Volume Method (FVM) and Finite Element Method (FEM) under a two-way coupling method. In order to find a better understanding of the dynamic FSI response and stability of flexible lifting bodies, the fluid flow is modeled in the different turbulence models and cavitation conditions. The flow-induced deformation and elastic response of both rigid and flexible hydrofoils at various angles of attack are studied. The effect of three-dimension body, pressure coefficient at different locations of the hydrofoil, leading-edge and trailing-edge deformation are presented and the results show that because of elastic deformation, the angle of attack increases and it lead to higher lift and drag coefficients. In addition, the deformations are generally limited by stall condition and because of unsteady vortex shedding, the post-stall condition should be considered in FSI simulation of deformable hydrofoil. To evaluate the accuracy of the numerical model, the present results are compared and validated against published experimental data and showed good agreement.

A Hybrid Numerical Model to Address Fluid Elastic Structure Interaction

2016 ◽  
Author(s):  
Manoj Kumar Gangadharan ◽  
Sriram Venkatachalam
Keyword(s):  
Numerical Model ◽  
Fluid Structure Interaction ◽  
Breaking Waves ◽  
Elastic Structure ◽  
Navier Stokes ◽  
Breaking Wave ◽  
Ocean Engineering ◽  
Fluid Structure ◽  
Strongly Coupled ◽  
Structure Interaction

Hydroelasticity is an important problem in the field of ocean engineering. It can be noted from most of the works published as well as theories proposed earlier that this particular problem was addressed based on the time independent/ frequency domain approach. In this paper, we propose a novel numerical method to address the fluid-structure interaction problem in time domain simulations. The hybrid numerical model proposed earlier for hydro-elasticity (Sriram and Ma, 2012) as well as for breaking waves (Sriram et al 2014) has been extended to study the problem of breaking wave-elastic structure interaction. The method involves strong coupling of Fully Nonlinear Potential Flow Theory (FNPT) and Navier Stokes (NS) equation using a moving overlapping zone in space and Runge kutta 2nd order with a predictor corrector scheme in time. The fluid structure interaction is achieved by a near strongly coupled partitioned procedure. The simulation was performed using Finite Element method (FEM) in the FNPT domain, Particle based method (Improved Meshless Local Petrov Galerkin based on Rankine source, IMPLG_R) in the NS domain and FEM for the structural dynamics part. The advantage of using this approach is due to high computational efficiency. The method has been applied to study the interaction between breaking waves and elastic wall.

scholarly journals Two-way strongly coupled fluid-structure interaction simulations with OpenFOAM

2019 ◽  
Vol 405 ◽  
pp. 012007
Author(s):  
Benjamin Doulcet ◽  
Christophe Devals ◽  
Bernd Nennemann ◽  
Maxime Gauthier ◽  
François Guibault ◽  
...  
Keyword(s):  
Fluid Structure Interaction ◽  
Fluid Structure ◽  
Strongly Coupled ◽  
Structure Interaction
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