[FLASH-USERS] Interpreting pressure behavior in the SinkRotatingCloudCore test problem

[Lewis,Sean]

Hello all,

In my work towards modeling a protoplanetary disk, I have consistently encountered an interesting behavior in gas pressure. Specifically, a region of low pressure around the collapsed cold gas cloud that is generally about 10x lower than the pressure of the outer regions of the cloud as well as the surrounding less-dense gas. I have attached a few .png files from the out-of-the-box SinkRotatingCloudCore test problem to illustrate what I mean. The images are taken at 34kyr and 50kyr taken looking down the z-axis, and another 50kyr snapshot looking down the x-axis to see the side-view of the forming disk.

How can this effect be interpreted? Something physical that’s expected? Something numerical that is (un)expected? Initially, I thought that the dense gas cloud was contracting towards its center of mass faster than the surrounding halo gas, creating a vacuum of sorts. However, I have seen the same effect in other simulations of mine where the dense gas is nearly relaxed into a disk though to a lesser degree and the same effect is not seen in plots of the gas density. This makes me think this could be an artifact of the equation of state solver in some way.

With appreciation,

Sean Lewis
Drexel University


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