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<p>Hello all,<br>
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<p>I have two things that I could really use some help with, and I haven't been able to figure it out by myself.<br>
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<p>Firstly, I've been trying to run a simulation in 2D with a spherical geometry, but a few steps after starting the simulation the code crashes due to a negative dt.<br>
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<p>I set the density and temperature constant in the simulation, and the velocity to 0, so nothing should be happening (just as a test case).<br>
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<p>I'm attaching a plot of the density just before the crash. <span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);">I</span><span style="font-family: Calibri, Arial, Helvetica, sans-serif; font-size: 16px; background-color: rgb(255, 255, 255);">'m
guessing the problem lies in the grid somewhere, but I have no idea how to fix it.</span><br>
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<p>Have any of you encountered something like this before?<br>
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<p>Secondly, and the reason I've been wanting to switch to a spherical geometry, is the results of simulating shocks in 2D using a Cartesian geometry.<br>
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<p>I ran some simulations with a spherical shock (outward radial velocity from a dense region), and found that the shock doesn't develop the same way in 2D as it does in<br>
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<p>3D Cartesian. The shock tends to move much faster, as if it is encountering less resistance or has too much kinetic energy.<br>
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<p>Shouldn't it be possible to have a 2D Cartesian slice of a spherical outward shock? Are these issues simply due to the geometry or from an error in setting up the problem?<br>
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<p>I would really love some help on this, since I've just been trying unsuccessfully to fix it on my own.<br>
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<p>Kind Regards,<br>
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<p>Michiel Bustraan<br>
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