Changes between Version 1 and Version 2 of AstroBearProjects/WindDiskInteraction


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Timestamp:
09/06/11 17:51:07 (13 years ago)
Author:
Jonathan
Comment:

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  • AstroBearProjects/WindDiskInteraction

    v1 v2  
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    33= Conservation of Angular Momentum =
    4   While the code conserves momentum, it does not explicitly conserve angular momentum.  To test this we setup a 2D disk around a point gravity source. 
     4  While the code conserves momentum, it does not explicitly conserve angular momentum.  To test this we setup a 2D disk around a point gravity source with a density contrast of 100.  Pictured below is the angular momentum.  The left panel has a truncated color scale to show the effects of periodic boundaries as well as the transport of angular momentum from the disk into the ambient.  Also shown are contours of angular velocity corresponding to .5, 1, and 2 rotations over the course of the simulation.  The right panel is a zoom of the disk itself without a truncated color scale.  Here is the [attachment:AngMom.gif movie]
     5
     6[[Image(AngMom0100.png, width=800)]]
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     8We also did an explicit query of the total angular momentum as a function of time.  Over the course of the simulation the total fractional change in angular momentum is only .00081 or less then .1% It is likely that the loss of angular momentum is due to numerical dissipation at the center of the disk, although with levels so small it is difficult to rule out boundary effects.  Although the symmetry of the problem should keep the net angmom transport from the boundaries to zero.
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     10[[Image(AngMom.png, width=800)]]