Recently several works have been published on numerical simulation of an external gear pump (EGP). Such kinds of pumps are simple and relatively inexpensive, and are frequently used in fluid power applications, such as fluid power in aeronautical, mechanical, and civil engineering. Nevertheless, considerable effort is being undertaken to improve efficiency and reduce noise and vibration produced by the flow and pressure pulsations. Numerical simulation of an EGP is not straightforward principally for two main reasons. First, the gearing mechanism between gears makes it difficult to handle a dynamic mesh without a considerable deterioration of mesh quality. Second, the dynamic metal-metal contact simulation is important when high pressure outflow has to be reproduced. The numerical studies published so far are based on a two-dimensional (2D) approximation. The aim of the present work is to contribute to the understanding of the fluid flow inside an EGP by means of a complete three-dimensional (3D) parallel simulation on a cluster. The 3D flow is simulated in a LINUX cluster with a solver developed with the OPENFOAM Toolbox. The hexahedral mesh quality is maintained by periodically replacing the mesh and interpolating the physical magnitudes fields. The meshing contact point is simulated with the viscous wall approach, using a viscosity model based on wall proximity. The results for the flow rate ripples show a similar behavior to that obtained with 2D simulations. However, the flow presents important differences inside the suction and the discharge chambers, principally in the regions of the pipes' connection. Moreover, the decompression slot below the gearing zone, which can not be simulated with a 2D approximation, enables a more realistic simulation of a contact ratio greater than 1. The results are compared with experimental measurements recently published.

Three-Dimensional Numerical Simulation of an External Gear Pump With Decompression Slot and Meshing Contact Point

Suspensions with deformable solid inclusions have both scientific and industrial interest. Examples include microgel particle suspensions, biological fluids, and filled polymers. Due to the interplay of numerous factors (e.g., particle size, shape, and mechanical properties, suspending liquid rheology and flow conditions, flow cell shape, interactions between the particles and the flow channel and among the particles), these systems can show many different flow behaviors. The study of the flow behavior of soft particle suspensions is an open field and is attracting an increasing interest from the scientific community. As elastic beads are good models for biological cells, one reason for such interest is related to the possibility of exploiting particle mechanical-property-dependent flow behavior to diagnose diseases. On the other hand, in the recent years, suspensions of elastic microparticles are also proving useful in a completely different technological field, namely oil recovery from porous media. This paper gives an overview of the state of the art and envisages possible future perspectives on the dynamics, rheology, and applications of elastic particle suspensions.

Dynamics, rheology, and applications of elastic deformable particle suspensions: a review

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A Nonlinear Computational Model of Tethered Underwater Kites for Power Generation

Effect of hydrophobicity on the water flow in carbon nanotube—A molecular dynamics study

This paper presents a computational model for the ammonothermal gallium nitride (GaN) crystal growth process, including fluid flow, heat transfer, dissolution and crystallization rates, GaN metastable phase transport, and crystal interface advancement. The presented article solves the Navier–Stokes equations along with the Brickman–Darcy–Forchheimer extensions for nutrient porous medium and Boussinesq approximation for free convection. Piecewise Linear Interface Calculation (PLIC) method is adopted to construct and advance the crystal interface. Simulations, in particular, were performed for a common research autoclave with a retrograde ammonothermal system. Special attention is given to the regions close to the crystal interface.

Heat, mass, and crystal growth of GaN in the ammonothermal process: A numerical study

In this study, a numerical algorithm is developed for simulating the interaction between a fluid and a 2D/axisymmetric hyperelastic body based on a full Eulerian fluid-structure interaction (FSI) method. In this method, the solid volume fraction is used for describing the multicomponent material and the deformation tensor for describing the deformation of the hyperelastic body. The core elements of the simulation method are the constitutive law in the Cauchy stress form and an equation for the transport of the deformation tensor field. A semi-implicit formulation is used for the elastic stress to avoid instability especially for solid with high stiffness. The strain rate has a discontinuity across the fluid/ solid interface. For improving the accuracy in capturing the interface, solid is treated as a highly viscous fluid. The viscosity term has the effect of smoothing the velocity and keeping the simulation stable. An experimental setup is used to validate the numerical results. The movement of a sphere made of silicone in air and its impact on a rigid substrate are investigated. The images are captured using a high speed CCD camera and the image processing technique is employed to obtain the required data from the images. For all cases considered, the results are in good agreement with those of the experiment performed in this study and other numerical results reported in the literature. [DOI: 10.1115/1.4027893]

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H. Esmailzadeh

Papers

Numerical and Experimental Analysis of the Fluid-Structure Interaction in Presence of a Hyperelastic Body