December 2017 - Nektar-users

how to use HOBC?
by Kurt Sansom 25 Mar '18

25 Mar '18

Hi, I am trying to use the higher order outlet boundary conditions. I know that is formulated for truncated open domains, but am curious if I can use in the following way, where I want to specify the outlet pressure to some value to create back pressure in the system. I realize that for in-compressible flow it doesn't matter that much, but I am interested in implementing a time varying pressure condition at the outlet. I have tried the following boundary condition for a tube and it doesn't appear to apply the VALUE tag? I want to make sure before I file a bug. <REGION REF="2">  <N VAR="u" USERDEFINEDTYPE="HOutflow" VALUE="0" /> <N VAR="v" USERDEFINEDTYPE="HOutflow" VALUE="0" /> <N VAR="w" USERDEFINEDTYPE="HOutflow" VALUE="0" /> <D VAR="p" USERDEFINEDTYPE="HOutflow" VALUE="10665" /></REGION> Regards, ~Kurt -- Kurt Sansom

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Re: [Nektar-users] NAN time integration error
by SIDHARTHA SANKAR SAMANTARAY 20 Dec '17

20 Dec '17

Hello, Sorry I didn't know about the non-confirming mesh problem. Now I have prepared a conforming mesh (file attached). Can you please check whether it is okay? It is also showing NAN. Thanks. On Tue, Dec 19, 2017 at 7:31 PM, SIDHARTHA SANKAR SAMANTARAY < sss12(a)iitbbs.ac.in> wrote: > Hello, > Sorry I didn't know about the non-confirming mesh. Now I have prepared a > conforming mesh by just clicking on 2D mesh option in gmsh. Can you please > check whether it is okay? It is also showing NAN. I am online, so you can > ask me anything more you want. > > Thanks. > > On Tue, Dec 19, 2017 at 6:47 PM, Douglas Serson <d.serson(a)gmail.com> > wrote: > >> Hi Sidharth, >> >> Your geo file looks fine to me. However, I noticed a couple of problems >> in the mesh of the xml you just sent. >> First, composites 2 and 3 are switched compared to the geometry in the >> geo file (and to what I think makes sense in terms of boundary conditions). >> Also, the mesh near the inflow is non-conforming, as you can see in the >> attached image (i.e. one edge of the large element is connected to 3 >> different elements). This is not supported by Nektar++. >> How exactly did you generate this mesh? Using your geo file I obtained a >> completely different mesh from gmsh. >> >> Cheers, >> Douglas >> >> 2017-12-19 6:37 GMT-02:00 SIDHARTHA SANKAR SAMANTARAY <sss12(a)iitbbs.ac.in >> >: >> >>> Hi Douglas, >>> Thanks a lot for the solution. I found that line was in every code of >>> mine. But even after correcting that line, the same error can be seen with >>> a structured mesh. I am sending you the gmsh script this time. Please tell >>> me whether structured mesh has to be taken care in a special way. And >>> another thing i want to know is whether each grid should be orthogonal to >>> run the solver? >>> >>> Regards, >>> Sidharth >>> >>> On Tue, Dec 19, 2017 at 2:06 PM, SIDHARTHA SANKAR SAMANTARAY < >>> sss12(a)iitbbs.ac.in> wrote: >>> >>>> Hi Douglas, >>>> Thanks a lot for the solution. I found that line was in every code of >>>> mine. But even after correcting that line, the same error can be seen with >>>> a structured mesh. I am sending you the gmsh script this time. Please tell >>>> me whether structured mesh has to be taken care in a special way. And >>>> another thing i want to know is whether each grid should be orthogonal to >>>> run the solver? >>>> >>>> Regards, >>>> Sidharth >>>> >>>> On Tue, Dec 19, 2017 at 3:02 AM, Douglas Serson <d.serson(a)gmail.com> >>>> wrote: >>>> >>>>> Hi Sidharth, >>>>> >>>>> I checked your xml file and it is missing a </REGION> on line 90. >>>>> By fixing this I was able to start the simulation without getting a >>>>> NaN. >>>>> >>>>> Cheers, >>>>> Douglas >>>>> >>>>> 2017-12-18 9:57 GMT-02:00 SIDHARTHA SANKAR SAMANTARAY < >>>>> sss12(a)iitbbs.ac.in>: >>>>> >>>>>> Hello, >>>>>> I am seeing NAN time integration error while solving a simple problem >>>>>> with compressible NS solver. Can anyone tell me what is probably causing it? >>>>>> I have attached the screenshot of the error and the xml file running >>>>>> the solver. >>>>>> >>>>>> Thanks, >>>>>> Sidharth >>>>>> >>>>>> ------------------------------ >>>>>> *Disclaimer: *This email and any files transmitted with it are >>>>>> confidential and intended solely for the use of the individual or entity to >>>>>> whom they are addressed. If you have received this email in error please >>>>>> notify the system manager. This message contains confidential information >>>>>> and is intended only for the individual named. If you are not the named >>>>>> addressee you should not disseminate, distribute or copy this e-mail. >>>>>> Please notify the sender immediately by e-mail if you have received this >>>>>> e-mail by mistake and delete this e-mail from your system. If you are not >>>>>> the intended recipient you are notified that disclosing, copying, >>>>>> distributing or taking any action in reliance on the contents of this >>>>>> information is strictly prohibited. >>>>>> _______________________________________________ >>>>>> Nektar-users mailing list >>>>>> Nektar-users(a)imperial.ac.uk >>>>>> https://mailman.ic.ac.uk/mailman/listinfo/nektar-users >>>>>> >>>>>> >>>>> >>>> >>> >>> ------------------------------ >>> *Disclaimer: *This email and any files transmitted with it are >>> confidential and intended solely for the use of the individual or entity to >>> whom they are addressed. If you have received this email in error please >>> notify the system manager. This message contains confidential information >>> and is intended only for the individual named. If you are not the named >>> addressee you should not disseminate, distribute or copy this e-mail. >>> Please notify the sender immediately by e-mail if you have received this >>> e-mail by mistake and delete this e-mail from your system. If you are not >>> the intended recipient you are notified that disclosing, copying, >>> distributing or taking any action in reliance on the contents of this >>> information is strictly prohibited. >>> >> >> > -- ------------------------------ *Disclaimer: *This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited.

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NAN time integration error
by SIDHARTHA SANKAR SAMANTARAY 19 Dec '17

19 Dec '17

Hello, I am seeing NAN time integration error while solving a simple problem with compressible NS solver. Can anyone tell me what is probably causing it? I have attached the screenshot of the error and the xml file running the solver. Thanks, Sidharth -- ------------------------------ *Disclaimer: *This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the system manager. This message contains confidential information and is intended only for the individual named. If you are not the named addressee you should not disseminate, distribute or copy this e-mail. Please notify the sender immediately by e-mail if you have received this e-mail by mistake and delete this e-mail from your system. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited.

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Using a specified discrete velocity profile as a inflow boundary condition
by 李依然 03 Dec '17

03 Dec '17

Dear all, I'm now trying to define a inflow boundary condition using a specified discrete velocity profile when simulating with the IncNavierStokesSolver. Specially, the inflow velocity profile I use here is a Blasius profile. Since it is numerically solved by an external code, the profile here is in discrete form (i.e. velocity on discrete points). While from the user guide, I can see that a profile with an explicit expression can be directly implemented as a boundary condition in the .xml file, it seems that there is few examples on how to deal with a specified discrete velocity profile. I wonder if there is any way to implement this kind of boundary condition in Nektar++? P.S.: To solve this problem, I wonder if the module "interppointdatatofld" of FieldConvert should be used? If so, how to use it for the boundary? Besides, I think here a ".bc" file which is mentioned in 3.3.5.5 Boundary conditions from file in user guide might be needed, but I don't know how to construct this kind of files? Thanks in advance for the help. Best Regards, Mona

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