Development of CFD Inverse Analysis Technology Targeting Heat or Concentration Performance Using the Adjoint Method and Its Application to Actual Components

To resolve two major problems of conventional CFD-based shape optimization technology: (1) dependence of the outcome on the selection of design parameters, and (2) high computational costs, two types of innovative inverse analysis technologies based on a mathematical theory called the Adjoint Method were developed in previous studies for maximizing an arbitrary hydrodynamic performance aspect as the cost function: surface geometry deformation sensitivity analysis to identify the locations to be modified, and topology optimization to generate an optimal shape. Furthermore, these technologies were extended to transient flows by the application of the transient Adjoint Method theory. However, there are many cases around flow path shapes in vehicles where performance with respect to heat or concentration, such as the total amount of heat transfer or the flow rate of a specific gas component, is very important. Therefore, a new inverse analysis technology for CFD that can select arbitrary heat or concentration performance aspects as the cost function was developed. The calculation of surface geometry sensitivity distributions targeting these aspects was enabled for both steady-state and transient problems including fluid-solid conjugate problems by extending the formulations to the transport equations of scalar quantities (i.e. temperature or concentration), expanding the Adjoint variables, and improving the solution methodologies. The validity of the sensitivities calculated by developed program was verified through test cases including a steady-state heat transfer problem and a transient concentration problem. It was confirmed that applying these surface geometry sensitivities to design changes was as effective as targeting hydrodynamic performance by applying the developed technologies to actual components, including the cooling flow performance of a power control unit (PCU) assembly, and the improvement of multi-cylinder distribution balance of EGR gas in an engine intake flow system followed by the trial shape modifications.