University of Puerto Rico Mayaguez INGE 4016 Fluid Mechanics

University of Puerto Rico Mayaguez INGE 4016: Fluid Mechanics -CFD-Computational Fluid Dynamics First Semester 2016-2017 This assignment carries out a CFD simulation of an incompressible Newtonian fluid flow in a circular pipe in different flow regimes. Some of the objectives are to introduce the concept of meshing, boundary conditions, residuals and convergence and how to use CFD calculations as an engineering tool. Also, the numerical results are compared with theoretical results to validate the simulation and to reinforce concepts that have been studied in the course. For this assignment use the provided mesh to run the simulation, and assume the following: axis-symmetric flow pipe diameter D 0.02 m, length of the pipe L-0.2 m The fluid is air, with the following properties p 1 kg/m, and 2x10 Pa s Reynolds number ReD 100. In the first part of this assignment the flow field in the entrance region of a circular pipe is investigated for the laminar regime. The pressure and velocity profiles are analyzed along the pipe and compared to analytical results. Recall that the Navier-Stokes equations (the governing equations of a Newtonian fluid are non-linear and have to be solved iteratively. After running the simulation until convergence is achieved, compare your results with the analytical results obtained and discuss the following concepts: a. Plot the centerline pressure distribution as a function of distance along the pipe. Explain why a portion of the plot is linear and a portion is nonlinear. What does the theory predict? What is the pressure drop per unit length?

Solution

a) Linear non linear parts: at BL the profile is non linear, after wards above BL linear

b) level off as core regioon approoached

c) plot and show core is inviscid (linear profile)

d) this is due to development of fully developed flow

BEST!!