[CIG-LONG] Help! SNAC Benchmark: Parallel-Plate Viscometer

[Jean Liu]

Hi Eunseo,

In the no-slip case, my velocities are still greatest on the wall  
boundary condition (instead of where it's supposed to be pushing out  
in the x-direction), and I get the shear and normal stress from the  
SNAC output, visualized on Paraview.

How do you get stress invariant as an output? When I load the .vts and  
.pvts files into Paraview, I get the option of plotting:

- plastic strain
- strain rate
- pressure
- hydrostatic pressure
- tetra shear stress
- max. shear stress
- von mises stress
- shear stress @30d
- normal stress @30d
- failure potential @30d
- phase
- viscosity
- velocity
- force
- temperature





Quoting Eunseo Choi <echoi at ldeo.columbia.edu>:

> I see. Then, the stress value you compute must be different from what's
> plotted in the manual.
>
> First of all, velocity field looks better in the no-slip case?
> And, what does the plot of stress invariant look like?
> How did you get the shear and normal components of stress?
>
>
> Eunseo
>
>
>
> On 08/11/2010 05:04 PM, Jean Liu wrote:
>> Hi Eunseo!
>>
>> I tried that before, as well, and I ended up getting an asymmetric   
>> pattern for stress.. (I attached the screenshot to this email)
>>
>> - Jean
>>
>>
>>
>>
>> Quoting Eunseo Choi <echoi at ldeo.columbia.edu>:
>>
>>> Hi, Jean
>>>
>>> No-slip conditions should be added on the moving walls.
>>> So, insert the following block of XML code into each of the top and
>>> bottom BC sections:
>>> ==================
>>> <struct>
>>> <param name="name"> vx </param>
>>> <param name="type"> double </param>
>>> <param name="value"> 0.0 </param>
>>> </struct>
>>> <struct>
>>> <param name="name"> vz </param>
>>> <param name="type"> double </param>
>>> <param name="value"> 0.0 </param>
>>> </struct>
>>> ==================
>>>
>>> And please update me on the results!
>>> Thanks.
>>>
>>> Eunseo
>>>
>>> ps. Do you mind posting this reply on the cig-long list?
>>>
>>>
>>> Jean Liu wrote:
>>>> Hi Eunseo!
>>>>
>>>> I thought it was straightforward, too, but when I ran it, my    
>>>> velocity vectors looked a bit different from yours: my velocities  
>>>>   were greater at the wall velocity boundary condition, then at   
>>>> the  part where the material is being squeezed out. Plus, to   
>>>> compare to  the second invariant of stress, I just added the   
>>>> shear and normal  components on paraview and got different   
>>>> numerical values (but  similar patterns).
>>>>
>>>> Could you take a look at my input file? I'm not sure if it's a    
>>>> problem with my installation of SNAC (when I ran make check,   
>>>> there  were quite a few Fails), or if everything is okay..
>>>>
>>>> I also attached a screenshot of my Paraview results.
>>>>
>>>> Thanks for all of you help again, Eunseo!! I'm sorry for being   
>>>> such  a nuisance..
>>>>
>>>> - Jean
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> Quoting Eunseo Choi <echoi at ldeo.columbia.edu>:
>>>>
>>>>> Dear Jean
>>>>>
>>>>> I produced the benchmark results but don't have the original input file.
>>>>> As far as I remember, it should be straightforward to construct an
>>>>> input file for that problem.
>>>>> What are the problems you ran into?
>>>>>
>>>>> Eunseo
>>>>>
>>>>> Jean Liu wrote:
>>>>>> Hi!
>>>>>>
>>>>>> I was wondering if anyone has the input file for the SNAC    
>>>>>> benchmark  parallel-plate viscometer problem that was used for   
>>>>>>  the figures in  the SNAC manual?
>>>>>> I'm trying to get a comparison for my output, but I'm running    
>>>>>> into  a  few problems...
>>>>>>
>>>>>> Thanks!
>>>>>>
>>>>>> - Jean
>>>>>>
>>>>>> _______________________________________________
>>>>>> CIG-LONG mailing list
>>>>>> CIG-LONG at geodynamics.org
>>>>>> http://geodynamics.org/cgi-bin/mailman/listinfo/cig-long
>>>>>>
>>>>>
>>>>>
>>>>> -- 
>>>>> =====================================
>>>>> Eunseo Choi
>>>>> Post-Doctoral Research Scientist
>>>>>
>>>>> Lamont-Doherty Earth Observatory
>>>>> 305c Oceanography
>>>>> P.O. Box 1000
>>>>> 61 Rt. 9W
>>>>> Palisades, NY 10964-8000
>>>>>
>>>>> http://www.ldeo.columbia.edu/~echoi
>>>>> Phone: 845-365-8813 Fax: 845-365-8156
>>>>> =====================================
>>>>
>>>>
>>>> ------------------------------------------------------------------------
>>>
>>>
>>> -- 
>>> =====================================
>>> Eunseo Choi
>>> Post-Doctoral Research Scientist
>>>
>>> Lamont-Doherty Earth Observatory
>>> 305c Oceanography
>>> P.O. Box 1000
>>> 61 Rt. 9W
>>> Palisades, NY 10964-8000
>>>
>>> http://www.ldeo.columbia.edu/~echoi
>>> Phone: 845-365-8813 Fax: 845-365-8156
>>> =====================================
>>
>>
>
>
> -- 
> =====================================
> Eunseo Choi
> Post-Doctoral Research Scientist
>
> Lamont-Doherty Earth Observatory
> 305C Oceanography
> P.O. Box 1000
> 61 Rt. 9W
> Palisades, NY 10964-8000
>
> http://www.ldeo.columbia.edu/~echoi
> Phone: 845-365-8813 Fax: 845-365-8156
> =====================================