Numerical Flow Analysis of The Variation of Central Axial Velocity Along The Pipe Inlet

Abstract

Due to no slip flow condition at the wall, thefluid enter the pipe with a smooth velocity start to develop along the flow tocomply the zero velocity at the wall and maximum at the pipe center. After acertain distance where the development completed, the velocity profile becomesfully developed and no longer changes observed along the pipe flow. The regionflow where the velocity profile developes is called developing flow or inletflow and the region flow where the fully developed profile govern are calledfully devloped flow. Computation of the flow properties in the fully developedregion can be enabled with various empirical theories, but the complex flowstyructure in pipe inlet region still has not been solved exactly. However Itis quite important to know the flow behavior at the pipe inlet to compute theright pumping power especially in the fluid heating and cooling short pipe flowprocesses. the study performed, the steady pipe flows with Newtonian fluid weresimulated numerically at low Reynolds numbers (ranged 1000 and 25000 ) coveringthe three flow regimes (laminer, transition and turbulence). High turbulencelevel and smooth velocity profile were assigned to the flow at pipe inlet.Turbulence flows were solved according to the time mean flow assumption. On thenumerical results obtained, the variation of axial central velocity along theflow was examined for different relative roughnesses. Consequently, a numericalcorrelation which define the axial velocity and fit the numerical values wellis proposed.