[CIG-LONG] Re: Re: Re:Re: Re: Cumulative strain history in Gale et alia -, Stokes, example (Walter Landry) (Walter Landry)

[Christoph Schrank]

Hi, Walter,

thanks a lot. Argh, how could I forget that? Ultimately I was aiming at 
3D experiments as well but switched it off for the first tests to save 
computation time (I do not have easy access to supercomputers). We use 
this 3D test quite often to determine densities of analogue materials 
with well-constrained viscosities since we have access to a 
high-precision rheometer, so I use this equation by default. Anyways, I 
am glad to hear that it was my fault rather then a problem with the 
code! I am looking forward to seeing the corrected results. If I have a 
free machine I will start something on the side as well.

Thanks again,

Cheers

Christoph

cig-long-request at geodynamics.org schrieb:
> Send CIG-LONG mailing list submissions to
> 	cig-long at geodynamics.org
>
> To subscribe or unsubscribe via the World Wide Web, visit
> 	http://geodynamics.org/cgi-bin/mailman/listinfo/cig-long
> or, via email, send a message with subject or body 'help' to
> 	cig-long-request at geodynamics.org
>
> You can reach the person managing the list at
> 	cig-long-owner at geodynamics.org
>
> When replying, please edit your Subject line so it is more specific
> than "Re: Contents of CIG-LONG digest..."
>
>
> Today's Topics:
>
>    1. Re: Re:Re: Re: Cumulative strain history in Gale et	alia -
>       Stokes, example (Walter Landry) (Walter Landry)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 16 Oct 2007 00:20:45 -0700 (PDT)
> From: Walter Landry <walter at geodynamics.org>
> Subject: Re: [CIG-LONG] Re:Re: Re: Cumulative strain history in Gale
> 	et	alia - Stokes, example (Walter Landry)
> To: cig-long at geodynamics.org
> Message-ID: <20071016.002045.230888381.walter at geodynamics.org>
> Content-Type: Text/Plain; charset=us-ascii
>
> Christoph Schrank <schrank at geology.utoronto.ca> wrote:
>   
>> Hi, Walter,
>>
>> I wanted to simulate the classical simple Physics experiment with a
>> solid ball falling in a fluid in a pipe where the frictional force
>> is given by:
>>
>> F_r = 6phrv,
>>
>> lifting force by: F_l = -r_fluid V_ball g,
>>
>> and Fg=r_ball V_ball g. Adding these up to zero for constant sinking
>> velocity leads to: v_sink =(2/9)(r_ball - r_fluid )r^2 g/h.
>>     
>
> These calculations are for a sphere.  However, the simulation is in
> 2D, so we need to use calculations for a cylinder.  That changes the
> drag force to 
>
>   4*pi*viscosity*velocity/log(3.70*viscosity/(velocity*radius*density))
>
> The buoyancy force is
>
>   pi*radius^2 * (density_ball - density_fluid)*gravity
>
> Doing a nonlinear solve for the velocity gives
>
>  velocity=0.0026914
>
> which is almost ten times larger than the case for the sphere.  The
> number you were getting (about 0.0004) is off because of the proximity
> of the boundary.  As you increase the distance from the cylinder to
> the boundaries, you get larger velocities.  However, running the code
> in 3D should give you the lower velocity (0.00027778).  I am wrestling
> with my supercomputer account, but when I get that fixed, I will run
> 2D and 3D cases.
>
> Cheers,
> Walter Landry
> walter at geodynamics.org
>
>
>
>
> ------------------------------
>
> _______________________________________________
> CIG-LONG mailing list
> CIG-LONG at geodynamics.org
> http://geodynamics.org/cgi-bin/mailman/listinfo/cig-long
>
>
> End of CIG-LONG Digest, Vol 13, Issue 10
> ****************************************
>
>
>   

-- 
______________________
Christoph Schrank

University of Toronto
Department of Geology
Earth Sciences Centre

22 Russell Street
Toronto, ON, M5S 3B1
Canada

phon:

Lab:     416 946 7365
Office: 416 978 0833