Direct numerical simulations (DNS) are performed to investigate the physics of a spatially developing turbulent boundary layer flow suddenly subjected to spanwise oscillating electro-magnetic forces in the near-wall region. To generate time-dependent inflow data, the rescaling technique proposed by Lund et al. (1998) is used. The Reynolds number based on the inlet momentum thickness $θ_{in}$ and free-stream velocity $U_∞$ is $Re_θ=300$. A fully-implicit fractional step method is employed to simulate the flow. The mean flow properties, the Reynolds stresses and their budgets are obtained to analyze the near-wall turbulent structure. It is found that skin-friction and turbulent kinetic energy can be reduced by the electro-magnetic forces. The changes in the normal Reynolds stresses are mostly due to changes in the production. Instantaneous flow visualization techniques are used to observe the response of streamwise vortices to spanwise oscillating forces. The near-wall vortical structures are clearly affected by spanwise oscillating electro-magnetic forces.
