Shock tube simulaton
Introduction:
The shock tube divided in two pressure regions where Nitrogen exists in the high pressure regions and oxygen exists in the low pressure region. Both of these regions are seperated by a diaphragm.
This presssure difference would cause the diaphagm to break and a shock wave to propagate inside the tube.
Boundary conditions:
The shock tube has no inflow or outflow. In High pressure region boundary type wall condition is enabled and slip type is enabled for velocity and a temperature of 300K is specified as a given value.
Since the dimesnions are axis symmetric so 2D condition is used on front and back walls
Initial Condition:
6 bar pressure is defined in high pressure region where as 1 bar in low presssure region.
Adaptive mesh refinement is enabled with layer of 3 and sgs.embedded of 0.001.
Plots:
Pressure Plot
The above figure represents the variation in Pressure in the shock tube with respect to time. The pressure is steady till 0.0013 sec after which the diaphragm opens up and there is oscillation of waves for both max and mean preessure. Max presssure seems to be dropping with every cycle where as min pressure in increasing with every cycle. The average value of min pressure is around 0.2 MPa and max Pressure has an average value of about 0.5MPa.
Cell Count Plot
The cell count increases rapidly as the pressure in the high region opens up the diaphragm and cell count increases from 500 to about 40000 which is by factor of 80.
The animation for the velocity and speciies is provided in the link below: