Steady state simulation of flow over a throttle body

• Given Problem:-

Q. Simulate Flow of fluid over a throttle body in converge studio and post process the results

• Software used-

1. Converge CFD Software

2. Cgywin

3. Paraview

• Throttle body Step design-

• Steps Involved while solving this challenge-

1. We first download the required geometry from the website of skill lync.

2. Set the case setup according to the given problem in the challenge. As this steady state challenge we have set the case as steady state challenge.

3. Now we will check the given case for any problem and the export its files for running it into cgywin.

4. Cgywin willl create the output files of the case by solvig them.

5. Now we will open paraview software and open the case there. We will use glyph and streamline option to visualize and post process the result more clearly.

6. Now by using Converge software line plotting option, we will plot the graphs for Velocity, pressure and Mass flow rate.

• Case setup Important Parameters:-

1. Inlet Pressure- 150000 pa

2. Outlet Pressure- 100000 pa

3. Starting cycle- 0

4. Ending cycle- 15000

5. Solver- Pressure based steady solver

• Mesh, Velocity, pressure contour and plots

Fig.1.1 Mesh Profile of geometry

Fig.1.2 Velocity Profile(Top View)

Fig.1.3 Velocity Profile(Throttle View)

Fig.1.4 Velocity Profile over throttle

Fig.1.5 Pressure Profile

Explanation:-

1. Fig. 1.1; Its an slice view of geometry. We can see the surface with edges. As you all observe that near throttle position the edges are very dense. This is due to fact that we have done embedding on throttle area. The embedding increases edges count by multi fold. Now these edges will help us to simuate the case more precisely as number of cells increased.

2. Fig, 1.2; Velocity Profile which consist glyphs and streamlines to help us understand the case more better. As this picure is of final time step when the whole simulation is over. Due to that we can clearly see that Velocity is highest on throttle line and on throttle side. This due to fact that fluid will find minimum resistance above throttle and side of throttle. Due to this fact the fluid achieve its maximum velocity. The fluid which strike throttle will lose its velocity.

3. Fig. 1.3; Now lets see it more better. Lets take throttle as an symetrical airfoil(Lift is zero as angle of attack is 0 between throttle and fluid). The stream line or fluid is attacking throttle. Green stream lines(Low velocity) will come into contact with throttle and divide into two parts i.e. upper streamline and lower streamline. Now as AoA is 0, so the both streamline will meet at same time and become one after passing throttle.

Boundary layer which is most near to throttle will encounter a decline in velocity. Whereas

fluid layers above the boundary layers will be compressed by sudden encounter with throttle and due to pipe boundary. Now due to decrease in flow area, the fluid will increase its speed to maintain its flow rate. Thats why the velocity above throttle is increased suddenly as seen.

4. Fig. 1.4; Top most part of throttle is red whereas rest surface part is blue. It is easy to understand that boundary layer will experince low velocity due to friction but top layer will encounter faster velocity due the change in area. We already talked about this phenomena.

5. Fig.1.5; Pressure is high before encountering throttle whereas it decreases after passing through throttle. As pressure is inversely propotional to velocity, increase in velocity will decrease pressure in that region and hence we can see it clearly.

• Plots-

Fig. 3.6 Average Velocity variation during flow

Fig. 3.5 Total Pressure variation during flow

Fig. 3.4 Mass Flow rate variation during flow

Fig. 3.7 Total Cell count variation during flow