CFD modeling of single-phase flow in a packed bed with MRI validation

A computational fluid dynamic (CFD) model for single phase flow in the three dimensional randomly packed bed with spherical particles has been developed and validated with experimental results. The flow characteristics within this complex geometry are very complicated. In order to obtain insight into the interior and local flow characteristics, Three-dimensional simulation is required. First, we constructed the randomly packed bed with spherical particle, using Discrete Element Method (DEM) based on the integration of Newton’s laws of motion. To validate the DEM simulations the global bed porosity and the radial porosity distribution were compared with empirical correlation from literature. Second, the complex geometrical properties of random packed bed make it difficult to produce a fine mesh. Herein, the bridge method for meshing the particle-particle and particle-wall contact points in the packed bed was applied. The contact zones are modified and then partitioned into several regular parts, so the structure gird was meshed. Finally, the simulation of water flow in the randomly packed bed with a tube-to-particle diameter ratio of 6.325 has been carried out by the commercial CFD code. A comparison with previously published correlations and experimental data shows that the relationship proposed by KTA agree well with the measured pressure drop. Furthermore the results of simulation for distribution of velocity in the bed were analyzed and discussed.

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A Study Involving the Flow Pattern Comparison of a PIV Experiment With CFD Simulation, for the Flow Within a Centrifugal Pump

Volume 1A, Symposia: Advances in Fluids Engineering Education; Turbomachinery Flow Predictions and Optimization; Applications in CFD; Bio-Inspired Fluid Mechanics; Droplet-Surface Interactions; CFD Verification and Validation; Development and Applications of Immersed Boundary Methods; DNS, LES, and Hybrid RANS/LES Methods ◽

10.1115/fedsm2014-21688 ◽

2014 ◽

Author(s):

Md. Taifur Rahman ◽

Mohammed Siddiqi

Keyword(s):

Centrifugal Pump ◽

Single Phase ◽

Cfd Simulation ◽

Computational Simulation ◽

Test Subject ◽

Cfd Modeling ◽

Phase Flow ◽

Single Phase Flow ◽

Turbo Machinery ◽

Multi Phase

Computational Fluid Dynamics (CFD) modeling software is increasingly being used as the tool of choice for analyzing the flow details and integrated performance of turbo-machinery products. In fact, the use of CFD is rapidly transitioning from a verification tool to an upfront design-enabling & optimization tool. Experimental validation of computational simulation is essential to ensure an acceptable degree of reliability and relevance of the simulated results to real world performance. While CFD has been rigorously validated for numerous simple physics cases like single-phase flow, more complex physics applications, e.g., those involving multi-phase solid-liquid flows, require more elaborate and thoughtful means of validation. In this context, a study was undertaken to review Particle Image Velocimetry (PIV) as a means of validating more complex CFD cases and to contrast the findings with those obtained from CFD simulation. PIV offers a new possibility for flow visualization in turbo-machinery passages, in contrast to traditional methods like flow probing or hot-wire anemometry, which can be a very challenging proposition in the rotating domain of a turbo-machinery blade system. This paper discusses the first phase of this work, which was limited to single-phase flow studies, with the intent to follow up further with multi-phase flow studies. A specially designed fractional horsepower centrifugal pump is used as a test subject to analyze all possible parameters of the flow field using PIV and the result is then compared with the CFD simulations of the same model. The results show a reasonable match in the flow patterns obtained by the two alternate methods, although significant differences are apparent too. In conclusion, each method has its own place in the context of turbo-machinery flow studies.

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