Results from the advection loop test in 3D, showing a rendering of |B| in units of the initial value |B₀|. Top left panel: initial setup (same rendering for n_x = 128 and n_x = 256, and top right: uniform density case for GDSPH with resolution n_x = 128 after twenty crossings t = 20. We can see that the current loop is conserved almost perfectly even with all the dissipation terms turned on. This shows an improvement comparing to the SPMHD results in PHANTOM, where dissipation is seen after five periods (Fig. 35 in Price et al. 2018), which plots the current density. The bottom two panels show the cases with a density gradient between the inner loop and outer medium and with resolution of n_x = 256, after twenty crossings t = 20. The bottom left panel shows the GDSPH case and the bottom right show the TSPH case (n_x = 256). Both show similar dissipation of the magnetic field to the results from the MFM/MFV method in GIZMO (Hopkins & Raives 2016).