Reference no: EM132557068
GRID CONVERGENCE ANALYSIS
Question 1: Solve the flow of a jet of air at 25°C entering at Win = 0.8 cm/s into a plenum through a centered nozzle of d = 2.3 cm diameter, as in the figure below, and determine the ideal mesh that resolves the jet flow from the nozzle to a distance of 3 nozzle diameters into the plenum. Verify if the mesh is in the grid independent region.
(a) Introduce your simulation, giving schematic of domain with coordinate axes, boundary conditions, fluid used, advection scheme, estimated Red, laminar or turbulent flow (justify), and convergence criterion.
(b) Calculate a solution using a relatively coarse CFX mesh (initial grid). This mesh should be without inflation or heavy local refinement (advanced sizing is OK). but with enough resolution to evaluate the flow for proper grid refinement. Monitor the value of W at the centre jet point and plot the monitoring curve.
Plot the grid on an XZ plane across the centre of the jet, (show plane view) and a profile (chart) of the converged W velocity component along a horizontal line (parallel to the z-axis) in this plane at 3 diameters distance from the nozzle. Analyze the overall flow, based on your choice of relevant plots.
(c) Calculate another solution with your best locally refined mesh, with less than 500,000 nodes. Describe the mesh discretization and refinement procedures. Plot again grid and velocity profile.
(d) Coarsen systematically your best grid twice systematically to obtain two grids (medium and war) that have approximately the same number-of-nodes ratio. Analyze each result before your overall analysis.
(Hint: Use a number-of-nodes ratio of approximately 1.7, because of the limita-tions of this assignment. Ideally the node ratio should be larger.)
Plot the value of the maximum horizontal velocity at 3 diameters from the noz-zle, which is a quantity sensitive to the entire flow, as a function of the number of nodes (log-linear).
(e) Did you reach a grid independent (asymptotic) solution level? (Use the maximum horizontal velocity as your comparison variable.) Explain.
Even if you did not reach a grid independent solution, try to estimate the ex¬act value of the maximum velocity using Richardson Extrapolation, showing the calculation used.