Project Steady state simulation of flow over a throttle body

Objective: To simulate (Steady state) Flow of fluid over a throttle body in converge studio and post-process the results.

1. Show pressure and velocity contours.
2. Show the mesh (i.e surface with edges).
3. Show the plots for pressure, velocity, mass flow rate and total cell count.

Given: Geometry of Elbow structure with the throttle.

Geometry is made in Solidworks and saved as .STL file hereafter we placed the geometry in  CONVERGE CFD to proceed for simulation. Geometry cleanup and mesh generation will be done by widely commercially using CFD package i.e. CONVERGE CFD software.

Theory:

                                     Basics of the Throttling valve.

Valves that are used as fluid control devices are typically referred as \"Throttling valve\" 

Such valves experience internal velocity and internal pressure gradients (both positive and
negative) that conclude with a permanent pressure loss (∆P) from the inlet pipe-to-outlet pipe connections.
In looking into the thermodynamic principles of a “throttling process”, we know —

`Deltah= h_1-h_2`
`Delta h=0`

THE CHANGE IN ENTHALPY ACROSS A RESTRICTION IN A PIPE — ORIFICE, REGULATOR, CONTROL VALVE — IS “ZERO” FOR A THROTTLING PROCESS.

Case Setup:

`**`Import elbow.STL file into converge CFD
`**` Boundary flagging and Geometry cleanup is done with an additional checkpoint that All the normals pointing to the interior.
`**`As we are interested in simulating the non-reacting flow, no combustion or chemistry will be simulated. We are proceeding with a General flow application.
`**`We are doing gas simulation material we will be selecting is predefined mixtures is \"AIR\". 

`**`Simulation parameter:
Solver: Pressure based steady solver (For steady-state simulation)
Here, we are performing steady-state flow simulation because the throttle valve is not going to move and end results we will be expecting is the final complete flow field like Pressure, Velocity, Mass flow rate, etc.
Simulation time Parameter: It is set as

`**` Boundary Condition:
Inlet Boundary- Boundary Type: INFLOW
                          Pressure B.C.: 1.5e5 pa
                          Velocity B.C.: Zero Normal gradient (NE)
                          Temperature B.C.: 300 K
                          Species B.C.: Air (`O_2=0.23, N_2=0.77`)

Outlet Boundary- Boundary Type: OUTFLOW
                            Pressure B.C.: 1e5 pa
                            Velocity B.C.: Zero Normal gradient (NE)
                            Temperature B.C.: 300 K
                            Species B.C.: Air (`O_2=0.23, N_2=0.77`)

Throttle Boundary - Boundary Type: WALL
                                Velocity B.C.: Law of wall (when Flow is turbulent)
                                Temperature B.C.: 300 K (Law of wall)
                                tke B.C.: Zero Normal gradient (NE)
                                eps B.C.: Wall model

Elbow Boundary - Boundary Type: WALL
                             Velocity B.C.: Law of wall (when Flow is turbulent)
                             Temperature B.C.: 300 K (Law of wall)
                             tke B.C.: Zero Normal gradient (NE)
                             eps B.C.: Wall model

`**` Add volumetric region and assigned to all user-defined boundaries for initialization and application of boundary condition.
`**` Grid Control:
Base Grid: Base grid we will be working on is
`**`Fixed Embedding: The gap between the throttle plate and the throttle body wall is very small, a consequence of this is that cells also need to be small. One way to overcome this is to use different sizes of cells, small cells near and at the gap and larger in general.
Entity type - Boundary
Boundary ID - Throttle
Mode - PERMANENT
Scale - 3 
Embed layer - 2

Export all the input files to the folder after that we need to process files for convergence using converge.exe. Convert all processed files into ParaView VTK in-line binary format. 

3D Post-processing Results:

Mesh structure:

Here, the Lesser gap between throttle and throttle wall leads to lesser mesh size which will be done by using fixed embedding.

Pressure and Velocity contour plots:

From the pressure contour plot, we can say that there is major pressure drop from inlet to outlet of the elbow. There is a considerable decrease in static pressure which can cause flow separation after passing from a throttle valve

Show the plots for pressure, velocity, mass flow rate and total cell count.

Bound_id_3 - Inlet boundary
Bound_id_4 - Outlet boundary

Total Cell count:

Rank refers to the Numbers of processors we are using to run the simulation.
Rank0 - Processor 1
Rank1 - Processor 2

All the above plots are convergence plots which are converged to the exact solution after running simulation for some cycles.