| | 197 | == NLUF Shock Magnetized Clump Project == |
| | 198 | [[BR]] |
| | 199 | In the NLUF project, we conduct experiment to run shocks over target (SiO2) embedded in ambient (Argon), and study the projection image of the resulting flow pattern. The core of this project is to study the influence of added magnetic field. The field is on the direction vertical to the shock normal. The magnetic beta can be suppressed to around 10 by careful instrumentation. However, different from the ideal MHD case, the resistivity is not negligible in lab astrophysics. We run simulations to determine the effect of resistivity for the shocked clump problem. The set up is similar to a regular shock-clump interaction problem, however, the temperature profile is determined by the radiation from the side of the horam. This part of the simulation could be done by running steady state simulation using AstroBEAR's new radiation transfer functionality. [[BR]] |
| | 200 | http://www.pas.rochester.edu/~shuleli/NLUF_sep/setup.png [[BR]][[BR]] |
| | 201 | Temperature setup: [[BR]] |
| | 202 | 0.026ev in the ambient, 0.0012ev in the target initially, 0.026~0.8ev in the ambient, 0.0012~0.3ev in the target after preheated by radiation). The Spitzer resistivity has a floor temperature: any temperature below 0.26ev (3000K), is treated as 0.26ev when calculating resistivity. This means that only after preheating, the hot end of the target will start to diffuse magnetic field. [[BR]][[BR]] |
| | 203 | http://astrobear.pas.rochester.edu/trac/astrobear/attachment/blog/shuleli09072013/hydronew.png [[BR]][[BR]] |
| | 204 | |
| | 205 | Constant resistivity (magnetic Reynolds number is fixed), "Bx" (magnetic field parallel to the shock normal) case at around 3 clump crushing time scales. The Rm labeled in the figure is the magnetic Reynolds number. The plot at the bottom is the case where the fluid is perfectly conductive (Rm is infinite). [[BR]][[BR]] |
| | 206 | |
| | 207 | [[Image(http://www.pas.rochester.edu/~shuleli/Resistive_Clump/denpara_lr__0100.png, 70%)]][[BR]][[BR]] |
| | 208 | |
| | 209 | Here is a movie for it:[[BR]] |
| | 210 | [http://www.pas.rochester.edu/~shuleli/Resistive_Clump/denpara_lr.gif][[BR]][[BR]] |
| | 211 | |
| | 212 | The following figure is the "By" (magnetic field perpendicular to the shock normal) case at around 3 clump crushing time scales.[[BR]][[BR]] |
| | 213 | |
| | 214 | [[Image(http://www.pas.rochester.edu/~shuleli/Resistive_Clump/denperp_lr_0100.png, 70%)]][[BR]][[BR]] |
| | 215 | |
| | 216 | Here is a movie for it:[[BR]] |
| | 217 | [http://www.pas.rochester.edu/~shuleli/Resistive_Clump/denperp_lr.gif][[BR]][[BR]] |
| | 218 | |
| | 219 | We can see that although at Rm=100 still show quite a difference in the two field configurations, the difference is beginning to diminish. We will be doing production runs with high resolution (64 zones per clump radii) on the bluegene cluster in the next few weeks.[[BR]] |
| | 220 | |
| | 221 | Spitzer resistivity, Comparison animation for beta = 1, 10 and infinite: [[BR]] |
| | 222 | http://www.pas.rochester.edu/~shuleli/NLUF_sep/movieall.gif [[BR]][[BR]] |
| | 223 | |
| | 224 | AstroBEAR has resistivity implemented and calculates the amount of magnetic diffusion at every simulation cell given their density, temperature and ionization fraction. We have since obtained ionization table of Argon and SiO2 from Jaques at LLE (Z(rho,T)), and have implemented code to read the table and compute local resistivity with the correct Z value. [[BR]] |
| | 225 | Other design suggestions: eliminate the backwall shock and put in an ablator in front (density wall) [[BR]][[BR]] |
