Time evolution of a CRC of initial radius a in the WNM phase for model 𝒫. The results at 10 GeV, 100 GeV, 1 TeV, and 10 TeV are shown from the left to the right and the top to the bottom. Each panel presents three plots and shows CR pressure evolution as a function of space for three times (top), the CR pressure gradient evolution (middle), and diffusion coefficients (bottom). Blue, green, and red refer to t_1/2/4, t_1/2, and 4t_1/2, respectively. The initial CR pressure distribution is represented by a thin black dashed line. The same typography is used for the background diffusion coefficient. Numerical solutions are represented with solid lines while test-particle solutions are presented by dashed lines.