Channel Flow simulation in Converge CFD
Aim:
To simulate the steady flow through channel for diferent Mesh size in CONVERGE CFD and post process the result in Paraview.
Theory:
In this problem,the solver used is Preassure based steady state solver.
PISO:
PISO algorithm (Pressure implicit with splitting of operator) is a pressure-velocity calculation procedure for the Navier-Stokes equations. Developed originally for non-iterative computation of unsteady compressible flow, but it has been adapted successfully to steady-state problems. PISO involves one predictor step and two corrector steps and is designed to satisfy mass conservation using predictor-corrector steps. Generally it gives more stable results and takes less CPU time but not suitable for all processes. It gives Suitable numerical schemes for solving the pressure-velocity linked equation.
Geometry:
Box is created with centre (0.05,0,0) and with length 0.1,0.01,0.01 in X,Y and Z direction respectivaly.
Material used for Simulation:Air
Initial Condition:
Tempraure:300 k
Preassure: 101325 Pa
Boundary Condition:
1.Inlet
Type: INFLOW
pressure: 100001 Pa (Total Preassure)
2.Outlet
Type: OUTFLOW
pressure: 100000 Pa (Static Preassure)
3. Top and Bottom Walls
Type : Walls
4.Front wall
Type :2D
5.Back wall
Type :2D
Simulation Time Parameters:
The simulation is run for 15000 cycle but we have enabled the steady state monitor.Hence the simulation will stop when variation is within tolerance.
Mesh Size:
Simulation is run for 3 different mesh size as follow:
1. dx = 2e-4 m, dy = 2e-4 m, dz = 2e-4 m
2. dx = 1.5e-4 m, dy = 1.5e-4 m, dz = 1.5e-4 m
3. dx = 1.0e-4 m, dy = 1.0e-4 m, dz = 1.0e-4 m
Result:
1.Mesh size:2e-4 in all dx,dy and dz direction.
Mass Flow Rate:
Average Velocity:
Total Preassure:
Static Preassure:
Total Cell Count:
Velocity Profile:
Velocity profile is taken at the end of channel( at distance 0.1 m from inlet) in Paraview.
Velocity Contour:
Preassure Contour:
2.Mesh size: 1.5e-4 m in all dx,dy and dz direction.
Mass Flow Rate:
Average Velocity:
Total Preassure:
Static Preassure:
Total Cell Count:
Velocity Profile:
Velocity profile is taken at the end of channel( at distance 0.1 m from inlet) in Paraview.
Velocity Contour:
Preassure Contour:
3.Mesh size: 1e-4 m in all dx,dy and dz direction.
Mass Flow Rate:
Average Velovity:
Total Preassure:
Static Preassure:
Total Cell Count:
Velocity Profile:
Velocity profile is taken at the end of channel( at distance 0.1 m from inlet) in Paraview.
Velocity Contour:
Preassure Contour:
Conclusion:
1.For Mesh size 2e-4,1.5e-4 and 1e-4, Total cell count is approximately 25,000,45,000 and 1,00,000 respectivaly.So,as the mesh size decreases the total number of cel count increases and hence Computational time increases.
2.Mesh is coarse for mesh size 2e-4 and is finer for mesh size 1e-4.
3.From the plot of Mass Flow Rate,the values of mass flow rate at outlate are approximately same as inlet but with opposite sign.Hence it can be said that Mass is conserved.
4.The velocity profile has not attained the perfect parabolic shape yet,hence it can be said than flow has not reached steady state.
5.As the Mesh size decreases,Plots obtaiined are getting smoother.