N. Raettig, W. Lyra, H. Klahr
Recent studies have shown that baroclinic vortex amplification is strongly dependent on certain factors, namely, the global entropy gradient, the efficiency of thermal diffusion and/or relaxation as well as numerical resolution. We conduct a comprehensive study of a broad range and combination of various entropy gradients, thermal diffusion and thermal relaxation time-scales via local shearing sheet simulations covering the parameter space relevant for protoplanetary disks. We measure the Reynolds stresses as a function of our control parameters and see that there is angular momentum transport even for entropy gradients as low as $\beta=-{d\ln s}/{d\ln r}={1}/{2}$, which corresponds to values observed in protoplanetary accretion disks. The amplification-rate of the perturbations, $\Gamma$, appears to be proportional to $\beta^2$ and thus proportional to the square of the \BV ($\Gamma \propto \beta^2 \propto N^2$). The saturation level of Reynolds stresses on the other hand seems to be proportional to $\beta^{1/2}$. This highlights the importance of baroclinic effects even for the low entropy gradients expected in protoplanetary disks.
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http://arxiv.org/abs/1212.4464
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