SHOCK TUBE SIMULATION BY USING THE CONVERGE STUDIO

A shock tube is a device for studying shock waves. Prior to starting an experiment, a diaphragm inside the tube blocks any flow. You increase the pressure on one side, such as with a compressor, and then start the flow by rupturing the diaphragm. The gas expands down the other half of the tube.

Through optical means you can observe the flow and model the action of shocks. A pressurized tube of this type can store substantial amounts of energy, allowing for the study of quite violent flows—albeit for only very short periods.

This model studies the phenomena of shock waves inside a shock tube, by setting up a model that solves for the pressure and the velocity inside the tube.

Geometry Clean Up:

Once the geometry is imported, we have to do the following steps to setup the cases.

1. Diagnosis of the Geometry.

2.Boundary Flag

3.Normal

4.Checking the Boundary box for the dimension.

Case Setup:

After did the geometry cleanup, we have to set the case to run the simulation. Here we are running the transient case, because we are interested to capture the effect on the interaction area. If we want end result then we can use the steady state.

After setup the transient we have to create the region to specify the boundary. Since shock wave operated on two region, high pressure and low pressure region.

The above two figure shows the creation of the region and also we specify the species in the region respectively.

Once we create the region, we have to assign the region based on the boundary created.The below figure shows the assigned region.

Here we set the 2d cases, and we mention only the wall as a boundary and specify the region.

One of the important in this type of analysis is event. Event helps to make the flow at which time it will happen.

In this case we define the region as low and high pressure. In real case we have the diaphragm, but here with the help of event we can run the analysis. The above figure shows that, at 0 s both the region is closed that is there no interaction between the region after 0.01 S, the region is open, it mean two region going to interact and mixed with each other form the shock wave.

Here we are using the baseline mesh to run the analysis.

The above figure shows, the adaptive mesh refinement. Here we are using the AMR which we capture the species of N2 more accurately. Due to the amr the variation in the N2 region calculated with the more number of mesh elements.\\

Plotting:

The above figure shows the plotting image of pressure, temperature, and cell count of region o and region 1 respectively.

In pressure plot it is shown that the low pressure and high pressure and also the mean pressure value. Low pressure value due to the low region similarly for the high pressure region also. Since upto 0.001 secon we close the region that is there is no interaction, after that it clearly shows the deviation in the plot because of the interaction and the shock wave produced. The produced shock wave try to increase the temperature and also the pressure is reduced after the shock wave which is clearly shown in the plotting figure of pressure and the temperature.

In cell count it is also shows the effect of AMR where the number of cells is increased in the region 1 because of more N2 placed and changed abruptly.

Contour:

The above figure shows the mesh for the baseline grid size.

In paraview, the term idreg helps to identify the region. Here we are using the two region, which it showns in the above figure.

The above shows the effect of the AMR, here we interested in finding the changes in the species of N2, which it will show clearly in the above figure, where the mesh element is increased a lot on that area.

The above two figure shows the effect of pressure and the temperature respectively due to the shock wave.

Animation:

Conclusion:

From the above analysis, it is clearly shown the animation due to the high pressure and low pressure region interact, the disturbance happens on the fluid form the shock wave which increases the temperature and the pressure is reduced and also with the help of Adaptive mesh refinement we capture the species change in the tube.