In wrinkled flamelet regime of turbulent combustion, the reacting front in turbulent combustion is considered as a very thin interface between two non-reactive flows. Properties of the flame front remain unchanged from the laminar flame and the flame front is only wrinkled by the flow field. The resulting motion is mainly affected by the hydrodynamic interaction that makes the flow field be dependent on the wrinkled front. Numerical and experimental studies on the wrinkled flame front have been conducted in order to examine the flame/flow interaction in the time varying flow field. A flame model where the flame is regarded as a source of volume and vorticity. The flame surface is determined by conventional G-equation. To confirm the numerical simulation, the flame front behavior under the oscillating flow field is observed experimentally. From the results of numerical simulation and the experimental observation, it is clearly found that the upstream flow characteristics are modified by the motion of the curved flame front and that the hydrodynamic interaction between flame and flow results from the volume generation and vorticity production at the flame front. The vorticity production is found to be an integral part of velocity field, especially in time varying flow.