Fundamental Study on Laminar Boundary Layer Characteristics under Irregular Waves

Laminar boundary layer behavior under irregular wave motion has been investigated in this paper through numerical methods. The irregular wave velocity has first been generated and later used for flow computation in the boundary layer through low Reynolds number κ-ε model. The generation of irregular wave velocity shows a satisfactory result when compared with input spectral properties. Obtained k-ε model results have then been utilized for detailed analysis of time variation of bottom shear stress with freestream velocity. Model results show that the bottom shear stress is more dominated by high frequency component waves than that for velocity. It is also very sensitive to freestream velocity variations and does not always respond in the same way to similar velocity conditions. A comparison of irregular wave bottom shear stress with that of monochromatic waves shows that the significant bottom shear stress closely corresponds to that of sinusoidal wave computed with the highest two-third of wave heights (H2/3).