Effect of spatial development on convective heat transfer enhancement in a pipe with transverse vibration

The present study models the flow configuration in a tube downstream of multi-branching in a catalytic converter. Convective heat transfer in a thin circular straight pipe is analyzed by direct numerical simulation (DNS). Forced transverse vibration is applied to the pipe itself to enhance the heat transfer. The main computational domain is sufficiently long to capture the spatial development of the vibration effect with the inflow-outflow boundary condition. The representative Reynolds number is set to be less than that in a driver domain which generates the turbulent inflow of the main domain. Profiles of the Nusselt number exhibit that the positive effect of the vibration on the heat transfer becomes apparent at certain downstream locations. The distance to its location is short with the high vibration frequency keeping the amplitude constant. In the region where the heat transfer is enhanced, the main flow with high temperature is shifted to one side and the other side of the pipe wall in the vibration direction alternatingly with the appearance of the organized streamwise vortices. The flow structure in the present spatially developing configuration is governed mainly by the vibration frequency although the terminal heat transfer performance is approximately a function of the velocity amplitude of the vibration.