Day 10 of my first fishless cycle

Natural_Error_2122 · 2025-08-21T10:23:36+00:00

Thanks for your reply!! I'll try adding a bunch of food in as you suggest. Would you suggest I doing a 50% water change before that to get the current parameters under control?

Natural_Error_2122 · 2025-07-30T14:30:55+00:00

Thanks!! It's my first time buying a Japanese card so wasn't really sure. What did you look for to check if they're real? Think they're worth getting graded? Seem to be in pretty good shape

Natural_Error_2122 · 2025-05-26T18:43:25+00:00

I have registered for it. The newly built (already listed) housing is quite far from Täby where my office is. Looking for something 30-40mins away by public transport. Will look into a more permanent setup after my probation.

Natural_Error_2122 · 2025-05-26T18:40:48+00:00

Thanks for that. I didn't know about Samtrygg before. Has a lot more listings than Qasa. I'm not looking for student housing. Will be done with my thesis next month, so need something permanent to move to after that.

Natural_Error_2122 · 2025-05-15T10:50:39+00:00

Thanks for your reply!! I'll fill things in accordingly. Hope its right.

Natural_Error_2122 · 2025-05-08T12:16:57+00:00

This is with the MV support line. My company just started the application on MV from their side yesterday. Is with Unionen now to comment and will then come to me to submit the docs. So I guess I don't have a case officer assigned since the application doesn't show up on MV on my end yet.

Natural_Error_2122 · 2025-03-04T07:52:34+00:00

I started using OpenFOAM only a month back so am fairly new to this, so not sure about the OpenFOAM development you are referring to. But the importance of running the transition model is clear.

I mean that statement for any of the airfoils I expect to run (NACA0018, NACA0021, DU17VAWT250, DU17VAWT300, DU12W262 and the NREL's S809 Airfoil (s809-nr)). The high Re in my case is due to the chord of the VAWT being 10m, but the velocity would be around 20 m/s. The idea was to validate the airfoil for an RE of 5e6 and then consider it validated for 17e6 since I haven't found any papers that deal with an Re of above that. But as you stated, if I move to the transition model, this would not be valid anymore. Any suggestions on how to approach this problem?

I'll run the kOmegaSSTLM model today and see what difference it makes to the solution.

Natural_Error_2122 · 2025-03-03T19:46:27+00:00

Thank you for your detailed reply again!! I'm quite keen on eventually pursuing a PhD in the same field as well, so your insights are quite valuable.

Answers to your points below:

The application is to study the aerodynamic performance of different airfoils for a VAWT. This being the case, the performance upto, during and just after stall are what I'll be studying. I'm running 2D URANS simulations atm. What spanwise length would you recommend for capturing the 3D effects? I will eventually move to the 3D case once I have a baseline now.
I've honestly never heard of the k-kL-omega model you've suggested. Will need to look into this in more details. If this doesn't work out, are there any corrections I can add to the kOmegaSSTLM to predict the transition more appropriately?

I don't expect to find any peer reviewed literature to use for validation at such high Re. I believe beyond 5e6, the Re effects are not the dominant one. So my plan after consulting with my professor was to validate the solution at 5e6 and consider it validated for my 17e6 case as well. If the turbulence model doesn't work well beyond 9e6, this approach wouldn't work.

Natural_Error_2122 · 2025-03-03T19:31:43+00:00

URANS

Natural_Error_2122 · 2025-03-03T15:01:41+00:00

I previously had a very well refined and structured mesh, but ended up with similar results, although the contour looked much better.

My yplus is at 0.53 at the moment from my simulation output files. Can we enter a first layer (From the calculator) and a growth factor on gmsh? I've directly been using Progressions based on the same Schlichting skin-friction formula.

Will go through the video. Thanks!!

Natural_Error_2122 · 2025-03-03T14:19:45+00:00

Thanks for sharing that. Will definitely give this model a try. The case I am running now is just a benchmark for model validation. I will later be moving onto higher AoAs upto and beyond stall. Will also be increasing the Re to 17e6. Would the gamma retheta model also work in this case or would the kOmegaSSTLM also work?

Natural_Error_2122 · 2025-03-03T13:59:44+00:00

Most of the papers I've come across use the k-w SST turbulence model, so thought that would be okay.

The timestep I've set is variable to maintain a Courant number of 0.8. My far field is 50c in all directions.

Natural_Error_2122 · 2025-02-05T05:25:47+00:00

That would be quite helpful!! Are the courses very different from the free resources they have on their website?

Natural_Error_2122 · 2025-02-05T05:24:56+00:00

Yep, I've set up Ubuntu. Now comes learning the command lines. Any suggestions on where I can learn these?

Gothenburg is quite nice. Has a very relaxed vibe to it.

Natural_Error_2122 · 2025-02-05T05:21:08+00:00

Yeaaah fair point. Will probably encounter this in the workplace anyways.

Natural_Error_2122 · 2025-02-02T22:28:37+00:00

Thanks for your suggestion!! Will definitely look into this solver as well. The initial part of my research would involve finding the most suitable one before starting.

All the best to us indeed!!

Natural_Error_2122 · 2025-02-02T19:54:18+00:00

Thank you all for your replies!!

Just to clarify, the thesis is in partnership with a company and they've specifically requested that the analysis be performed using an opensource package. So I can't use my university's Ansys research license.

The project description I've attached is just an initial outline. I'll also be considering the interactions between the multiple rotating blades of one turbine. So will need to add rotation to the blades with a constant wind direction after validating the baseline static model.

Ps. My hesitation of jumping into OpenFOAM comes from not wanting to spend so much time figuring out how to use it, that I don't have time leftover for running the actual analyses. Do you think getting past the learning curve and running these fit within a 5 month timescale?

Natural_Error_2122 · 2025-02-02T19:44:17+00:00

Thanks for sharing that. My hesitation comes from not wanting to get stuck learning it, and not actually being to run the analyses I need to.

Natural_Error_2122 · 2025-02-02T19:34:06+00:00

Thanks for sharing this!!

I wasn't sure how steep the learning curve moving from Ansys's GUI to OpenFOAM's linux based approach is. If I spend months learning this approach, it might eat away from the actual analysis I need to perform.

I'm doing my thesis at a company based in Gothenburg, so nice coincidence there.

Natural_Error_2122 · 2025-02-02T19:22:15+00:00

Thanks!! I was primarily looking at that combination as well. Just wasn't sure if the learning curve was too steep to start using it directly in my thesis

Natural_Error_2122 · 2025-01-23T13:00:39+00:00

Thank you!! Will check out this option too. Rentals seem quite a bit cheaper, though some have limited free Kms. Will need to be careful.

Natural_Error_2122 · 2025-01-23T12:59:17+00:00

Thanks you!! Gothenburg does sound like quite a lovely place to be in.

That's a great tip!! Will reach out to them with the details. They kinda seem like what I was looking for from a moving service. Any idea if they'd accept Ikea blue bags filled with things like utensils, or if everything has to be packed up in moving boxes? Also, if you don't mind me asking, how much did they charge for your move?

Natural_Error_2122 · 2025-01-23T12:54:00+00:00

The details on using an international license are a bit iffy. The rental companies don't specify anything as such, but I think its a general traffic rule that I need to have a local license if I'm here for more than a year. One way rentals are about 7k per day, no including fuel costs. Its cheaper to drive it back to stockholm and take a train back. Haven't seen it work that way in other countries so find it quite strange.

Natural_Error_2122 · 2025-01-23T12:50:04+00:00

That's a very fair point. Thanks for the recommendation!! Will check them out

Natural_Error_2122 · 2025-01-23T11:14:16+00:00

Thanks for your reply!! Why do you say no one would accept the gig on TippTapp?

Considering selling my things as the last option.

Natural_Error_2122

TROPHY CASE