Date of Award
Master of Engineering Science
Mechanical and Materials Engineering
Prof. Roger E. Khayat
The wall jet flow driven by a pressure gradient near channel exit at Reynolds Number ranging from the order of 10 to 100, emerging from a two-dimensional channel is examined theoretically in this study. Poiseuille flow conditions are assumed to prevail far upstream from the exit. The problem is solved using the method of matched asymptotic expansions. The small parameter involved in the expansions is the inverse Reynolds number. The flow and pressure fields are obtained as composite expansions by matching the flow in the boundary-layer region near the free surface, flow in the outer layer region near the stationary plate, and the flow in the core region. The fluid is assumed to be Newtonian and it is found that the jet contracts downstream from the channel exit. The influence of inertia on the shape of free surface is emphasized and the boundary layer structure near the free surface is explored. To leading order, the problem is similar to the case of the free jet (Tillett 1968) with different boundary conditions. A similarity solution can be carried out using a similarity function which is then determined by solving a boundary-value problem, where the equation is integrated subject to the boundary conditions and a guessed value of the slope at the origin. The slope is adjusted until reasonable matching is achieved between the solution and the asymptotic condition far from the free surface. The level of contraction is essentially independent of inertia, but the contraction moves further downstream with increasing Reynolds number. The present work provides the correct conditions near exit, which are required to determine the jet structure further downstream. If the jet becomes thin far downstream, a boundary layer formulation can be used with the presently predicted boundary conditions for steady and possibly transient flows.
Azad, Md. Abul Kalam, "PRESSURE DRIVEN WALL JET FLOW NEAR CHANNEL EXIT AT MODERATE REYNOLDS NUMBER" (2011). Digitized Theses. 3481.