Heat transfer enhancement and torque reduction by traveling wave-like blowing and suction in turbulent Taylor-Couette flow

Direct numerical simulations of turbulent Taylor–Couette flows are performed to investigate the effect of a traveling wave control on torque and heat transfer. In the Taylor–Couette flow, inner and outer cylinders are rotating and immobile, respectively, and the temperature difference between cylinder walls is maintained as constant. The ratio between the inner and outer cylinder is 0.882, and the Reynolds number is set as 84,000. A traveling wave-like blowing and suction is imposed on an inner cylinder wall. A parametric study shows the effect of control parameters on torque and heat transfer. We focused on three characteristic parameter sets: heat transfer enhancement, relaminarization phenomenon, and simultaneous achievement of torque reduction and heat transfer enhancement. We employed identity equations by using three-component decomposition to clarify contributions from advection, turbulence, and diffusion on torque and Stanton number. The results indicated that the traveling wave control affects the turbulence and advection contributions.