[FLASH-USERS] boundary condition for symmetrical ablation

[Thibault Goudal]

Hi everyone, 

I've been runing 2D cylindrical FLASH simulations based on the LaserSlab setup. 
I would like to study the evolution of hydrodynamic instabilities at the ablation front. 

I attached bellow an illustration of the density map results. I only run the right side. The left part is built by the symmetry with the white axis at x=0. 
In white color, I circled what is my concern. This bubbly structure seems to show that the boundary symmetry at the left edge of the numerical box isn't what I expected to be a flat laser irradiation. 
It seems that at x=0, the laser deposition is lower. At late times, this impacts the instability growth on the axis. 

I used the "reflect" or "axisymmetric" hydro boundary on the axis. 
I also attached some parameters from the flash.par which could be relevant to fix my issue. 

I guess this is kind of a typical problem when you deal with such geometry. 
If you have any idea, I'll be glad to discuss about all of this. 

Thank you! 


# RADIATION/OPACITY BOUNDARIES 

rt_mgdXlBoundaryType = "reflecting" 
rt_mgdXrBoundaryType = "vacuum" 
rt_mgdYlBoundaryType = "vacuum" 
rt_mgdYrBoundaryType = "vacuum" 
rt_mgdZlBoundaryType = "reflecting" 
rt_mgdZrBoundaryType = "reflecting" 

#CONDUCTION BOUNDARIES 

diff_eleXlBoundaryType = "neumann" 
diff_eleXrBoundaryType = "neumann" 
diff_eleYlBoundaryType = "neumann" 
diff_eleYrBoundaryType = "neumann" 
diff_eleZlBoundaryType = "neumann" 
diff_eleZrBoundaryType = "neumann" 

#HYDRO BOUNDARIES 

# Hydro boundary conditions: 
xl_boundary_type = "reflect" 
xr_boundary_type = "outflow" 
yl_boundary_type = "outflow" 
yr_boundary_type = "outflow" 
zl_boundary_type = "reflect" 
zr_boundary_type = "reflect" 

# LASER PARAMETERS 

ed_laser3Din2D = .true. 
ed_laser3Din2DwedgeAngle = 0.1 

ed_lensX_1 = 1000.0e-04 
ed_lensY_1 = 0.0e-04 
ed_lensZ_1 = -1000.0e-04 
ed_lensSemiAxisMajor_1 = 1000.0e-04 
ed_lensSemiAxisMinor_1 = 1000.0e-04 
ed_targetX_1 = 0.0e-04 
ed_targetY_1 = 0.0e-04 
ed_targetZ_1 = 1400.0e-04 
ed_targetSemiAxisMajor_1 = 1000.0e-04 
ed_targetSemiAxisMinor_1 = 1000.0e-04 
ed_pulseNumber_1 = 1 
ed_wavelength_1 = 0.351 
ed_crossSectionFunctionType_1 = "gaussian2D" 
ed_gaussianExponent_1 = 4.0 
ed_gaussianRadiusMajor_1 = 900e-04 
ed_gaussianRadiusMinor_1 = 900e-04 
ed_numberOfRays_1 = 16384 
ed_gridType_1 = "radial2D" 
ed_gridnRadialTics_1 = 512 
ed_semiAxisMajorTorsionAngle_1 = 0.0 
ed_semiAxisMajorTorsionAxis_1 = "x" 





-- 
Thibault Goudal 
PhD Student CEA 
CELIA CNRS UMR5107 laboratory 
+33664160842 
thibault.goudal at u-bordeaux.fr 
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