Steady state simulation of flow over a throttle body
objective
Case setup for steady-state butter-fly valve means there no movement of the throttle valve, here objective set up appropriate boundary conditions and select proper solver to achieved steady-state solution.
case setup -
- geometry preparation and validation
- boundary flagging
- application
- materials
- simulation parameters
- boundary conditions
- initial parameters and conditions
- grid control
- post-processing
1.1 geometry preparation and transforming normal to the fluid domain
import .stl file of a butterfly valve in elbow tube (always check dimensions of file its should be metered)
transform all normal to the fluid domain.(use geometry dock-transform-normal)
2.1 boundary flagging
To assign boundaries geometry dock - boundary -flag
Important boundaries in this case setup are inflow, outflow, elbow wall, throttle body respectively.
3.1 application
- This case comes under general flow
4.1 materials
The predefined mixture is air gas simulation, reaction mechanism should be marked up.
4.1.1 gas simulation
Use suggested by the software.
4.1.2 global transport parameters
Use suggested by the software.
4.1.1 global transport parameters
Use as same as suggested by the software.
5.1 simulation parameter
5.1.1 run parameter
Use pressure-based solver, full hydrodynamic and compressible solver.
5.1.2 simulation time parameter
Set cycle from 0-15000 min-max time step as 1e-9.
5.1.3 solver parameter
Use suggested by the software.
6.1 boundary condition and initial condition and event
Goto initial condition and add region_0(a volumetric region where fluid flows), assign all region_0 to all boundaries in the boundary section.
For inflow
pressure BC as 1.5e5 pascals, And species boundary (fluid name) condition as the air.
For outflow
Pressure BC as 1e5 pascals, And species boundary (fluid name) condition as the air.
throttle as a stationary wall.
7.1 physical model
Use suggested by the software.
8.1 grid control
simulation base gid test 1 as 0.002
8.2 fixed embedding
Near throttle body
mode-permanent
scale-3
Embedded level-2
9.1 post-processing
- Use software suggested parameters for turbulence
- Use output file to control over post-processing file.
post-processing using ParaView
velocity contour with pressure contour on the throttle is shown
pressure contour
potting
plotting avg velocity vs cycle numbers
above image shows to archive steady-state for avg velocity pressure corrector algorithm repeats itself as 8698 times means at that cycle number it\'s achieved steady-state.
plotting cell counts vs cycle numbers
a total number of cells are 41454 that changes as fixed-embedded scale changes
plotting mass flow rate vs cycles
To achieved steady-state pressure corrector algorithm runs till 5052 cycles.
The time required to solve transport equations is given by tail log file and that 4617 seconds
conclusion
Here we have selected pressure-based solver to simulate the flow and runs simulation till 15000 cycles. Its observe that minimum 9000 cycles are required to achieve a steady-state. wall time required to solve is nearly 4617 seconds.