Square water explosion

This case is a 2D Cartesian test case. The square domain is composed of low-pressure air and high-pressure water is present at its center. Initial conditions are shown in Fig. 71. This test is referenced in ./libTests/referenceTestCases/PUEq/2D/squareWaterExplosion/. The corresponding uncommented line in ECOGEN.xml is:

<testCase>./libTests/referenceTestCases/PUEq/2D/squareWaterExplosion/</testCase>

Fig. 71 Initial condition before explosion.

The initial characteristics of the run are:

Characteristic	Value
dimension	1 m
Initial mesh size	80 x 80
boundary conditions	non-reflecting
final solution time	10 ms
solution printing frequency	0.2 ms
precision	Minmod

Results are shown in Fig. 72. There is a pressure gradient between the two regions. When the interface between the blue (air) and red (water) regions disapears, shock waves propagate in the air and the red region relaxes. This causes an increase in pressure inside the blue region.

With the help of the density evolution, shown in Fig. 72 through a Schlieren visualization, it is easy to observe that there is an explosion between the water and the air regions. The shock caused by the explosion propagates outward. After that, one can observe from the center (where the square was) phenomena reminiscent of Richtmyer–Meshkov instabilities.

Fig. 72 Water explosion over time. Schlieren visualization using Paraview software.