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چکیده
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In the present research, a model of vortex generation based on the viscous effect of fluid flow and the continuity of vorticity in the vicinity of wall has been introduced. Vorticity generates as the fluid adheres to solid boundaries and as a result, the wall skin friction plays the role of an external force acting on a thin layer of fluid attaching to the wall. This force has been treated as a body force in momentum equation and has been considered as the major reason of vorticity generation. A very thin contact layer of fluid close to the wall has been discretized to some contact elements; while to satisfy the external wall friction acting on the contact elements, each of elements has been broken to some vortex points. Inside the contact elements, vortex points move randomly and finally are released into the free stream, or find themselves out of fluid region. This method has been employed to solve an incompressible Newtonian fluid flow over a 2-dimensional flat plate. No-slip condition has been satisfied, and skin friction coefficient on the wall for a wide range of Reynolds Numbers has been compared with the Blasius solution. The rotational region of flow has also been compared with the Blasius boundary layer. The results have a good agreement with Blasius solution. The principal advantages of this method are that no empirical data is used, and the proposed method of vortex generation can be appropriate in some applications that local velocity and skin friction near the wall is vital.
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