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distributions_of_shocks_in_simulations [2020/06/16 18:44]
al copy and past from emails 		distributions_of_shocks_in_simulations [2020/06/19 10:38] (current)
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 +**Distributions discussed during the meeting :**
 +
 +**__Reminder :__**
 +
 +  - The sound speed in the code units is 0.25.
 +  - Slow shocks are in blue.
 +  - Fast shocks are red.
 +  - Rotational discontinuities are green.
 +  - Parker sheets are cyan.   
 +
 +**__Info :__**
 +
 +Distributions are no longer normalised, the numbers on the y axis are therefore numbers of scans. I kept only the best identifications we have (purest wave decompositions). It just makes distributions cleaner and analysis simpler. ​
 +
 +{{:​abc_v_scan.png?​540 |}}
 +
 +{{:​ot_v_scan.png?​540 |}}
 +
 +{{:​abc_v_perp.png?​540 |}}
 +
 +{{:​ot_v_perp.png?​540 |}}
 +
 +{{:​abc_v_perp1.png?​540 |}}
 +
 +{{:​ot_v_perp1.png?​540 |}}
 +
 +{{:​abc_vperp_norm.png?​540 |}}
 +
 +{{:​ot_vperp_norm.png?​540 |}}
 +
 **Andrew**: ​ **Andrew**: ​
 Here's a cartoon understanding I have for Thibaud'​s distributions from today'​s meeting. Here's a cartoon understanding I have for Thibaud'​s distributions from today'​s meeting.
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 **Thibaud**:​ **Thibaud**:​
 I am actually doing it, but it's a lot of data and my internet connection is not very fast here... I'll tell you if is bimodal too.  I am actually doing it, but it's a lot of data and my internet connection is not very fast here... I'll tell you if is bimodal too. 
 +
 +[Update :]
 +
 +{{:​abc_b_scan.png?​540 |}}
 +
 +{{:​ot_b_scan.png?​540 |}}
  
 **Andrew**: **Andrew**:
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 At the very high angles the relative shear blows up. I say relative shear because the velocity vectors are normalised to the shock velocity. So while the shear looks like it's growing, the shock velocity is in fact decreasing, and as said in the previous email these ever decreasing mach numbers are no longer interesting because they don't dissipate much. At the very high angles the relative shear blows up. I say relative shear because the velocity vectors are normalised to the shock velocity. So while the shear looks like it's growing, the shock velocity is in fact decreasing, and as said in the previous email these ever decreasing mach numbers are no longer interesting because they don't dissipate much.
  
 +**Pierre**:
 +Would it be possible to show velocity shears in units of the sound speed in these diagrams ?
 +
 +This way we don't have to factor out the relative proportions with respect to shock speed, and we can compare more directly to Thibaud'​s results.
 +
 +**Andrew**:
 +Ok I think I've done this. Here are sweeps of slow and fast shock parameter spaces, with transverse shift velocities relative to the sound speed.
 +Left shows the phase speeds tuned to allow slow shocks with mach numbers up to ~2.5
 +Right shows phase speeds tuned to allow fast shocks with mach numbers 1.5 and 2 (I wanted to keep the mach numbers low because I think you guys were finding very low mach numbers in the simulations,​ correct me if i'm wrong here)
 +Middle panel shows the transverse velocities caused by the shocks, with circles for slow shocks and squares for fast shocks and line styles matching their source.
 +
 +{{:​distr10_shear1.png|}}
 +
 +Here's the same kind of thing, but for fast shocks with 2 different magnetic field strengths: vA = cs and vA = 0.5cs
 +
 +This shows the shears are weaker when you reduce the field strength, which I guess is obvious because the shears are caused by magnetic tension.
 +
 +{{:​distr10_shear2.png|}}
 +
 +And for slow shocks, here are two sets of identical shock velocities (vs=1.2*cs*cos(theta) and vs=1.8*cs*cos(theta)) but on the left we have a "​weak"​ magnetic field such that vA = 2*cs and on the right a "​strong"​ field such that vA = 3*cs.
 +
 +{{:​distr12_shear3.png|}}
 +
 +So as usual higher shock velocities lead to higher shear velocities. But for a fixed shock velocity lower magnetic field strength gives higher shear velocity.
 +
 +**__Magnetic field increments__**
 +
 +{{:​abc_b_perp.png?​540 |}}
 +
 +{{:​ot_b_perp.png?​540 |}}
 +
 +{{:​abc_b_perp1.png?​540 |}}
 +
 +{{:​ot_b_perp1.png?​540 |}}
 +
 +{{:​abc_bperp_norm.png?​540 |}}
 +
 +{{:​ot_bperp_norm.png?​540 |}}
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