[FLASH-USERS] Z-pinch equilibrium simulation

[Tomasz Plewa]

Dear Zahra -

Any chance you could visualize the effective "force" (difference between 
gradient of thermal and magnetic pressure, I imagine) that defines the 
equilibrium?

Also, how many zones per pressure scale height do you have in your 
model? One typically wants to have at least 10 cells.

Tomek
--
On 4/7/21 11:44 AM, Zahra Seifollahi Moghadam wrote:
> Dear FLASH users,
>
> We have recently used FLASH MHD module for 2-D cylindrical (R-Z) 
> simulation of Z-pinch equilibrium. We have initialized our simulation 
> with Bennett equilibrium profiles for density and magnetic field and 
> zero velocity all over the domain. More details in the following 
> reference:
>
> K. Tummel et al., “Kinetic simulations of sheared flow stabilization 
> in high-temperature Z-pinch plasmas,” Physics of Plasmas, vol. 26, no. 
> 6, p. 062506, Jun. 2019, doi: 10.1063/1.5092241.
>
> We have used periodic BC for inlet and outlet, axisymmetric BC for 
> r=0, and reflecting BC for r=Rmax. When we ran our simulation without 
> any perturbation seed. Even though we expected to see a stable pinch 
> for the whole simulation time and velocity remaining zero, the pinch 
> was only stable and in equilibrium for some time and we observed 
> growing instabilities and an increase in radial velocity from zero to 
> factors of Alfven velocity. We attached two snapshots for t=0 and t=16 
> us of the simulations we ran to clearly illustrate the problem.
> We are wondering what could be the source of this problem and how this 
> problem could be possibly mitigated?
>
> Any comment and help are highly appreciated.
>
> Thanks,
> Zahra Seifollahi

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