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Thomas H. Kuehn, Fellow and David B. Kittelson, Co-Principal Investigator

Megasonic Cleaning and Ventilation of Occupied Spaces

Two projects are being pursued in this research with the objective of the first to develop an experimentally validated numerical model that will predict the acoustic energy distribution and particle removal forces on the surfaces of silicon wafers in an aqueous medium. The second project consists of developing an experimentally validated numerical model that will predict the steady-state velocity and temperature fields inside a room under non-isothermal conditions.

The main activity in modeling of megasonic cleaning systems has been comparing results with experimental measurements and obtaining a few more simulations for the original tank configuration. These researchers are modeling configurations being used in production or being considering for the future. Corresponding experimental activity is focused on the effect of dissolved gas on cavitation bubble formation.

Currently, modeling of megasonic cleaning systems consists of two parts. The first is to improve the model for the three-dimensional megasonic energy field in a specially designed, well instrumented megasonic cleaning tank. This type of tank is used to remove submicron particles from the surfaces of silicon wafers and electronic parts or to chemically process silicon wafers in a semiconductor manufacturing process. The second is to correlate cleaning efficiency (particle contaminant removal) with the local sound intensity distribution, the microstreaming field, and cavitation intensity distribution. The modeling method, calculated results, and final report provide industrial users information for evaluating and improving megasoic cleaning systems.

The work on LES applied to ventilatd enclosures has been obtaining background material and developing a realistic code on a small machine for tests. The serial basic code is working as expected on the workstations and on the IBM. The initial steps have been done to parallelize the code on the IBM using automatic parallelization. This work continues to add directives and message passing while the researchers gain experience with the Smagorinsky model.

The second project is a continuation of work on the simulation of large enclosure flows. A good set of experimental data has been obtained on such flows, and these researchers have simulated such flows using various two-equation turbulence models. The agreement between the data and the simulations is reasonably good for isothermal flows, but is not good when significant density differences exist. Large Eddy Simulations may be the best approach to predict the large-scale eddies observed in these flows.

This information is available in alternative formats upon request by individuals with disabilities. Please send email to alt-format@msi.umn.edu or call 612-624-0528.

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