NAFEMS International Journal of CFD Case Studies

Volume 2, February 2000

ISSN 1462-236X

Transient and Steady Flow Computations for an Electro-Mechanical System

Z. Pan and P. G. Tucker
Fluid Mechanics Research Center, School of Engineering, University of Warwick, Coventry CV4 7AL

https://doi.org/10.59972/lf72jdna

Keywords: Transient, Steady, Flow Computations, Electro-Mechanical System and Turbulence

Specification of Problem

The computation of transient turbulent flows has considerable engineering significance. During the period from the mid 1980's until now Computational Fluid Dynamics (CFD) has been used in a wide range of industries. The use of CFD in electronic/mechatronic system design is just one of many examples.
The flows in these systems effect component operating temperatures and also the deposition of contaminants. Both of these factors are strongly related to product reliability. As with many other engineering systems, most forced convection flows in electronics/mechatronics are transitional or turbulent. A significant amount of numerical work has been motivated by the need to predict fluid flow in electronic systems. Much of this is reviewed by Tucker (1997), being mostly for steady flows. However, Reindl et al. (1991) study transient laminar flow in a square enclosure with a heated wall. Also, Shy and Rao (1993) predict transient laminar free convection around an enclosed vertical channel. The application of CFD to mechatronics is discussed by Tucker and Hewit (1996).
The present work attempts to investigate the performance of turbulence models when predicting both transient and steady flows for the geometry presented in Figure 1. The flow inlet area shown has a suddenly opening shutter, giving rise to an in rush of air from an external air source. The geometry is quite specific being part of an electronic/mechatronic Automatic Teller Machine (ATM). However, the results produced here have a wider context. They are suggestive of the choice of turbulence models when predicting flows in systems with similar flow features. These include streamline curvature, large vortical structures and stagnation resulting from an impinging rectangular jet. The turbulence models tested include the standard k-ε model (Launder and Spalding, 1974), low (Wolfshtein, 1969) and high Reynolds number k-l models, and a standard mixing length (ml) model. Also, two zonal models are tried using the k-ε model away from walls with the k-l and ml models applied elsewhere.

References

Van Doormal, J. P. and Raithby, G. D., 1984, "Enhancements of the SIMPLE Method for Predicting Incompressible Fluid Flows", Numerical Heat Transfer, Vol. 7, pp.147-163.

Van Driest, E. R., 1956, "On Turbulent Flow Near a Wall", Aero. Sci., 23, pp 1007.

Gatski, T. B., and Speziale, C. G., 1993, "On Explicit Algebraic Stress Models for Complex Turbulent Flows", Journal of Fluid Mechanics, Vol. 254, pp. 59-78.

Jones, W. P. and Marquis, A. J., 1985, "Calculation of Axisymmetric Re-circulating Flows with a Second Order Turbulence Model", Proceedings of the 5th Symposium on Turbulent Shear Flows, Connel University, pp. 20.1-20.11.

Kato, M. and Launder, B. E., 1993, "The Modelling of Turbulent Flow Around Stationary and Vibrating Square Cylinders", Ninth Symposium on "Turbulent Shear Flows", Kyoto, Japan, pp. 10-4-1 - 10-4-6.

Launder, B. E. and Spalding, D. B., 1974, "The Numerical Computation of Turbulent Flows", Computer Methods in Applied Mechanics and Engineering, 3, pp.269-289.

Naylor, D. Floryan, J. M. and Tarasuk, J, D., 1991, "A Numerical Study of Developing Free Convection Between Isothermal Vertical Plates", Journal of Heat Transfer, Transactions of the ASME, Vol. 113, pp. 620-626.

Patankar, S. V. and Spalding, D. B., 1972, "A Calculation Procedure for Heat, Mass and Momentum Transfer in Three-dimensional Parabolic Flows", International Journal of Heat and Mass Transfer, Vol.15, pp.1787.

Patankar, S. V., 1980, "Numerical Heat Transfer and Fluid Flow, Hemisphere", New York.

Runchal, A. K., 1987, "CONDIF: A Modified Central-Difference Scheme for Convective Flows", International Journal for Numerical Methods in Engineering, Vol. 24, pp. 1593-1608.

Reindl, D. T., Beckman, W. A., Mitchell, J. W., Rutland, C. J., 1991, "Benchmarking Transient Natural Convection in an Enclosure", Presented at the National Heat Transfer Conference Minneapolis, MN, pp. 1-7.

Shyy, W. and Rao, M. M., 1993, "Simulation of Transient Natural Convection Around an Enclosed Vertical Channel", Journal of Heat Transfer, Transactions of the ASME, Vol. 115, pp. 946-954.

Speziale, C. G., 1987," On Non-linear k-1 and k-& models of Turbulence ", Journal of Fluid Mechanics, Vol. 178, pp. 459-475.

Tucker, P. G., 1997, "CFD Applied to Electronic Systems: A Review", IEEE Transactions on Components, Packaging, and Manufacturing Technology - Part A, Vol. 20, No. 4, pp.518 - 529.

Tucker, P. G. And Hewit, J. R. 1996, "CFD Techniques and their Relevance to Mechatronics", Mechatronics, vol 6, no 2, pp.193-207.

Wolfshtein, M. W., 1969, "The Velocity and Temperature Distribution in one dimensional flow with turbulence augmentation and Pressure Gradient", International Journal of Heat and Mass Transfer, 12, pp.301.

Cite this paper

Z. Pan, P.G. Tucker, Transient and Steady Flow Computations for an Electro-Mechanical System, NAFEMS International Journal of CFD Case Studies, Volume 2, 2000, Pages 103-118, https://doi.org/10.59972/lf72jdna