Cavitation is a phenomenon whereby vapor bubbles of a flowing liquid are formed in a local region where the pressure of the liquid is below its vapor pressure. It is well known that cavitation in torque converters occurs frequently when a car with an automatic transmission makes an abrupt start. Cavitation is closely related to a performance drop and noise generation at a specific operating condition in a car and a torque converter itself. This study addressed the relation between cavitation and performance in an automotive torque converter in a quantitative and qualitative manner using numerical simulations. The cavitation was calculated at various operating conditions using a commercial flow solver with the homogeneous cavitation model, and the torque converter performance was compared with the experimental data. Numerical results well match to the data and indicate that the cavitation causes significant performance drop, as the pump speed increases or both speed ratio and reference pressure decrease.

One of the most important parts of semiconductor etch tools is the electrostatic chuck (ESC), which ensures secure wafer holding during fabrication and uniform temperature distribution from center to perimeter of the wafer during plasma etching. In this study, we investigated the thermal and electrical analysis of the ESC to ensure the temperature uniformity of the wafer via analytical multi-physics simulation including backside gas (BSG) flow between the wafer and ESC surface while the high voltage direct current (HVDC) power was applied in the ESC. We devised a bipolar-Coulomb type ESC and compared experimental data with theoretical and computational results. The chucking pressure along the HVDC magnitudes from 500 to 1000 V was investigated through 1D electric circuit and 2D simulation using ANSYS Maxwell. And we investigated the temperature change of the wafer when the BSG pressure changes from 0 to 15 Torr through 1D thermal circuit and 3D simulation using ANSYS Fluent. The 1D equivalent electric circuit showed the same trend with an error rate of 6.94 % with 2D simulation and 58.75 % with an experiment on average. The 1D equivalent thermal circuit also showed the same trend with an error rate of 0.44 % with 3D simulation and 1.52 % with an experiment on average.