Week 4: Project - Steady state simulation of flow over a throttle body

Aim:

To Set up and run the steady state simulation for flow over throttle body.

Objectives:

• To Post process the results and show pressure and velocity contours.
• To Show the mesh (i.e surface with edges)
• To Show the plots for pressure, velocity, mass flow rate and total cell count.
• To Create an animation in which it throttle movement should be visible.

Procedure:

Step:1

Import given geomentry And modify the geomentry suitable for smulation.

By using the boundary fence option The outer layer is removed .

so that the free edges are poped and then it is rectified as using patch command.

This is the final geomentry ready for simulation.

Step:2:

In this step, flag them together as boundaries which are marked with different colours.

Giving boundaries by selecting the sides which can help with other steps for simulation.

Once the boundaries have been flagged, we assign the different boundary conditions for the flow to take place within the geometry.

Step:3:

Check whether there is any errors by using diagnosis tool as shown below.

Step:4:

These are the following steps for setting up simulation .

Step:5:

Select the application type time based for steady state simulation.

Step:6:

Select the material type for the flow through geomentry .here Air is the material taken.

Step:7

Select steady state solver for the simulation.and also pressure based

Step:8

In Steady state monitor we can give minimum number of cycles for simulation .

Step:9:

Here we can define the start and end time for cycles of simulation

and also the initial and minimum time step.

Step:10:

The boundaries are to bounded to a region for the steady simulation.so that volumetric region are created with the species of air.

Step:11:

Here select the turbulance model that can be used for simulation.

Step:12:

In here the boundary conditions are Assinged to the regions and also the inlet conditions are given .

pressure and temperature are defined for inlet.

Inlet:

Throttle and elbow:

In here walls are defined to law of wall and temperature value is defined.

Outlet:

here the outlet pressure and temperature is given as specified value.

species used for simulation is defined in outlet.

Step:13:

The basic mesh size of the Geomentry is specified here.

Step:14:

Here the mesh scale for Throttle are specified as below.

It is used to refine the mesh for desired regions.

Step:15:

Finally the specified case setup file are exported to folder and run simulation.

The simulation for number of cycles are run in cygwin command window.

Step:16:

Post convert the files that is simulated in cygwin command window and file name is given .

Step:17:

Software used: ParaView As the simulation is binary files called “post” files are generated inside the output folder. These files have an extension *.out. Now these files are written by CONVERGE. These files contain information regarding the 3D flow field. We use a special software called ParaView that can read this flow information. However, before ParaView can do this, the files have to be converted to a form that ParaView can understand. This is done using a tool called post convert. After the conversion, we load the files into ParaView.

Results:

Mesh:

Contours:

Velocity :

As the flow Approches the throttle body it encounters a narrow opening between the elbow and throttle . the lowest velocity is absorbed behind the throttle as its abstruct the flow.

Pressure:

In here the pressure is highest in front of throttle body and lowest in narrow opening where velocity is highest.

Plots:

Velocity:

In velocity plot the velocity reaches the steady state in 4000-5000 cycles.since the throttle is not rotating steady state is easily achieved.

Pressure:

In pressure plot the outlet pressure increases initially due to the interactions with throttle body and remains constant after passing the throttle and achieve steady state.

Mass flow rate:

For steady state simulation it is important to check convergence has attained. so from mass flow rate The convergence of outlet flow has been covered. so that it is helpful to meet requirements.and it achieves steady state easily also obeys the law of conservation.

Total cells:

Animation:

In animation vedio of velocity through throttle it is clearly obsobs that velocity increases when flow through narroe opening.

Conclusion:

Steady state simulation over throttle body helps us to get an overview of how the flow profile varies over the given case .

We can observe that mass flow rate staisfy the continity equation in cfl case.

The velocity increases and also pressure decreases in the narrow opening of throttle body.

In this project i have learned to set up case for simulation through throttle body and also run command in cyigwin setup. these files are post processed as well.