Direct Numerical Simulation of Microbubble Drag Reduction on Superhydrophobic Surface based on Nek5000

The microbubble generation technology in the underwater vehicle is considered one of the promising techniques to reduce skin friction resistance. In the present work, the behavior of microbubbles over the superhydrophobic surface was simulated using the Nek5000 code based on the spectral element method. The 2-way coupling Euler-Lagrange approach was adopted to predict the microbubble dynamics with the assumption of a non-deformable and spherical one. The fully elastic collision model was implemented to consider the effect of wall-bubble interaction. The simulation domain was horizontal channel flow and one of the channel surfaces was set as a superhydrophobic surface. Two types of superhydrophobic surfaces, ridge type and post one, were adopted in the present work. The drag reduction effect by the void fraction of microbubble and superhydrophobic surface type were investigated in detail.