[FLASH-USERS] shock waves in water

[Maksim Kozlov]

Dear Flash users,
I would really appreciate it if somebody could help me with the following
issues. I am trying to use FLASH code to simulate convergence of
cylindrical shock waves in water. Shock waves are initiated by deposition
of energy into the strip of water. 5kJ of energy is introduced into a strip
of water (width of strip ~1mm and radius ~4.5 mm) with sub-microsecond
pulse FWHH~0.25 microseconds. Height of the simulated cylinder is  ~ 50 mm.
Pressure and sound speed are calculated from the tabulated Equation of
state (Los Alamos SESAME database) using a 2D spline-interpolation
algorithm. I managed to simulate converging shock using the HLL Riemann
solver provided with FLASH code. Results of my simulations were recently
published in PoP (please see attached). However I encounter the following
problems
1) I am unable to simulate realistic experiments where energy is deposited
into an array of copper wires. This would require simulation of two
different substances and I believe FLASH code does not have such
capabilities
2) When I am trying to introduce power into narrower strip of water (~100
microns) gradients become much higher which results in significant
oscillations around shock front and consequent crush of the code (imaginary
sound speed). I tried to use different Riemann solvers and artificial
flattening but these did not help.
3) As far as I understand, the adaptive mesh capability of FLASH code
increases resolution around shock fronts (high gradients).  Is there any
way to add additional geometric conditions for increasing resolution in
such a way that resolution is increased only around the axis of the
cylinder where shock converges.
I would really appreciate any advice on how to solve the above issues or at
least give me reference to publications on this subject.
Thank you very much!
Dr Maksim Kozlov
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