# equation of Stokes

 Register Blogs Members List Search Today's Posts Mark Forums Read

 April 18, 2005, 08:58 equation of Stokes #1 Martina Guest   Posts: n/a Hi, I'm working on the dynamic of alpine glaciers and I'm trying to resolve the full equations of Stokes with finite differences. Is there anybody that knows an algorithm to solve the full equations of Stokes without approximations? For the moment I'm working in 2 dimensions (x,z) and I have so the equations: -dp/dx + dtau_xz/dz = - dtau_xx/dy dp/dz + rho*g = dtau_xz/dy + dtau_zz/dz where p is the pression, rho the density of the ice, g the acceleration of earth and tau_ij are the deviatoric stresses. I have the boundary condition v=0 at the bottom and tau*n=0 at the surface (tau is the matrice of the tau_ij's an n is a vector normal to the surface). And finaly I have: eps_ij=1/2*(dv_i/dj+dv_j/di)=A*tau_star^m*tau_ij, where A is a const, m a paramenter (I tried 0 -> Newton, 2-> Glen) and tau_star the invariant of the stress tensor. Can anybody help me? I tried an iterative algorithm to get the velocity fields proposed by K.Hutter, but for the moment it doesn't converge! Is this possible with finite differences or have I to use other methods? Thanks a lot.

 April 19, 2005, 13:31 Re: equation of Stokes #2 Harish Guest   Posts: n/a For stokes flow you can try using boundary elements method.Also you need to be careful when applying finite difference schemes. I would suggest using an implicit scheme for non viscous space terms central difference scheme for viscous terms and explicit fourth order runga kutta for time marching . -H

 April 20, 2005, 04:52 Re: equation of Stokes #3 Martina Guest   Posts: n/a Thanks for your response. I do not yet trying to iterate in time, the aim for the moment is to determine the velocities for a given (fixed) geometry. What do you mean by "boundary elements method"? Ok for the different schemes, but with finite differences I can't solve my equations "straight forward" without makeing approximations, can you give me a hint? Thanks. Martina

 April 20, 2005, 09:25 Re: equation of Stokes #4 steph Guest   Posts: n/a For de transport-convectives terms : QUICK (warning in the numerical diffusion)

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Mihail CFX 7 September 7, 2014 06:27 Sas CFX 15 July 13, 2010 08:56 prashant FLUENT 0 March 7, 2008 08:05 Rajil Saraswat Main CFD Forum 2 June 9, 2003 07:21 Robert Main CFD Forum 0 December 20, 2002 03:14

All times are GMT -4. The time now is 14:15.