Gadge

Definitions

  • Chambers's Twentieth Century Dictionary
    • n Gadge gaj an instrument of torture (Browning).
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Usage


In science:

In this case, however, we use a Gaussian kernel, rather than the B –spline one implemented in GADGE T .
Hydrodynamic simulations with the Godunov SPH
Initial conditions are the same used by Springel (2005) to test the GADGE T SPH scheme.
Hydrodynamic simulations with the Godunov SPH
To further emphasise the different behaviour of the SPH-based (GADGE T and T RADS PH) and GSPH-based (G S PH and G S PH CW) schemes, we plot in Figure 3 the fractional variation of the entropy of particles as a function of their final position, ac ross the discontinuity.
Hydrodynamic simulations with the Godunov SPH
Quite clearly, entropy variation is only determined by the presence of weak shocks for the GADGE T and T RADS PH scheme and, therefore, can only have positive sign.
Hydrodynamic simulations with the Godunov SPH
Both GADGE T and T RADS PH schemes show pressure wiggles immediately before the shock wave, which is located at 35 < x < 37 (see the inset in the pressure panel in Fig. 2).
Hydrodynamic simulations with the Godunov SPH
Note that velocity wiggles are largest for GADGE T and smallest for G S PH .
Hydrodynamic simulations with the Godunov SPH
GADGE T run at the same position for the density variable (upper-left panel).
Hydrodynamic simulations with the Godunov SPH
The prominence of the pressure wiggles in the GADGE T simulation is due to the lack of thermal energy diffusion that characterises this hydrodynamic scheme.
Hydrodynamic simulations with the Godunov SPH
In order to reproduce the results reported for the GADGE T code on the web site of the Wengen tests, we carried out the KH test in this case using 442 neighbours.
Hydrodynamic simulations with the Godunov SPH
On the other hand, GADGE T produces a piling-up of particles at the onset of the fan, corresponding to an excess of particles having low velocities, at the same position.
Hydrodynamic simulations with the Godunov SPH
There, the standard limiter produces an accumulation of particles, similar to what we found when using the SPH GADGE T formulation.
Hydrodynamic simulations with the Godunov SPH
Pressure of gas particles as a function of their y coordinates for GADGE T (red dots) and G S PH (green dots), at time t = 2τKH , in correspondence of the same vortex shown in Fig. 6, 78 < x < 210 kpc, 161 < y < 237 kpc, −3.5 < z < 5.5 kpc.
Hydrodynamic simulations with the Godunov SPH
In this case, th e entropy conserving GADGE T scheme develops arms, but fails to capture the development of the vortexes.
Hydrodynamic simulations with the Godunov SPH
Development of the Kelvin-Helmholtz instabilities at different times, as described by the GADGE T (upper panels), G S PH - I 0 2 (central panels) and G S PH (bottom panels) scheme.
Hydrodynamic simulations with the Godunov SPH
Already at early times, t = 4 (left panels), the GADGE T simulation develops less hydrodynamical instabilities in the up-wind part of the blob.
Hydrodynamic simulations with the Godunov SPH
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