Experimental investigation of flow in a rectangular cavity with a porous opening

The velocity field within a nominally two-dimensional cavity is investigated in a water channel. The Reynolds number based on cavity length and freestream speed is in the range 245--410. The purpose of the study is to characterize the changes in the recirculation flow pattern inside the cavity caused by a porous surface (rectangular mesh) covering the cavity opening. Both flow visualization and quantitative results for the mean and fluctuating velocity field are discussed for surfaces of different porosity ranging between 64.8% and 37.3%. The total kinetic energy, vorticity distribution and related circulation in the cavity are analyzed. The most significant finding is the huge reduction in total kinetic energy when the cavity opening was covered with the mesh for all cases. It is observed that parameters such as positioning of mesh with respect to cavity, length of mesh exposed to flow gap between the cavity and mesh also affect the flow field inside the cavity. And finally suggestions are made to minimize the flow field inside the cavity.