Flow simulation in a complex fluidics using three turbulence models and unstructured grids

Abstract

Purpose

The purpose of this paper is to simulate the behaviour of the symmetrical turn‐up vortex amplifier (STuVA) to obtain insight into its maximum through‐flow operation within the eight‐port STuVA, and understand the relation between its design parameters and flow characteristics. Furthermore, it is to test the performance of different turbulent models and near‐wall models using the same grid, the same numerical methods and the same computational fluid dynamics code under multiple impingement conditions.

Design/methodology/approach

Three turbulence models, the standard k‐ε, the renormalization group (RNG) k‐ε model and the Reynolds stress model (RSM), and three near‐wall models have been used to simulate the confined incompressible turbulent flow in an eight‐port STuVA using unstructured meshes. The STuVA is a special symmetrical design of turn‐up vortex amplifier, and the simulation focused on its extreme operation in the maximum flow state with no swirling. The predictions were compared with basic pressure‐drop flow rate measurements made using air at ambient conditions. The effect of different combinations of turbulence and near‐wall models was evaluated.

Findings

The RSM gave predictions slightly closer to the experimental data than the other models, although the RNG k‐ε model predicted nearly as accurately as the RSM. They both improved errors by about 3 per cent compared to the standard k‐ε model but took a long time for convergence. The modelling of complex flows depends not only on the turbulence model but also on the near‐wall treatments and computational economy. In this study a good combination was the RSM, the two layer wall model and the higher order discretization scheme, which improved accuracy by more than 10 per cent compared to the standard k‐ε model, the standard wall function and first order upwind.

Research limitation/implications

The results of this paper are valid for the global pressure drop flow rate. It should be desirable to compare some local information with the experiment.

Originality/value

This paper provides insight into the maximum through‐flow operation within the eight‐port STuVA to understand the relation between its design parameters and flow characteristics and study the performance of turbulence and near wall models.

Citation

Wang, J. and Priestman, G.H. (2009), "Flow simulation in a complex fluidics using three turbulence models and unstructured grids", International Journal of Numerical Methods for Heat & Fluid Flow, Vol. 19 No. 3/4, pp. 484-500. https://doi.org/10.1108/09615530910938399