科研之友
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摘要
To study the internal dynamics of dusty interstellar clouds bound by an inter-cloud medium, we have written a one-dimensional numerical code for dusty gas dynamics in two-phase media. The governing equations for both cloud and inter-cloud media are solved using a Godunov-type scheme. The interface between the cloud and inter-cloud media is tracked by a mesh in the arbitrary Lagrangian-Eulerian frame. The dust component is treated as either a pressureless continuum or super-particles. The dust-gas drag is described by either the Epstein law or the Baines relation. To minimize errors from source terms, we utilize (in time integration) an explicit fourth-order Runge-Kutta scheme. This code is specially designed and tuned for simulating the complicated dynamics of dusty interstellar clouds. We have run three sets of test problems: the first set comprises shock-tube tests. The resulting shocks are resolved with two or three grid points. The second set is to examine the degree of error convergence. The results at various spatial resolutions demonstrate the second-order spatial accuracy of our code. The third set involves the Bonnor-Ebert sphere. From a number of simulations, we could numerically determine the Bonnor-Ebert criterion with errors less than 6%. As an example of utilizing our code, we simulate the collapse of dusty clouds embedded in a radiation field. Inside the cloud, the dust grains drift inward by radiation field and the dust-to-gas ratio at the intermediate radius increases by a factor of 20.
- 出版日期2011-2-20
