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u/BDady

r/aerodynamics r/reptiles r/FluidMechanics r/mw3 r/CFD r/ObsidianMD
▲ 8 r/ObsidianMD

How do you manually size images in the new update?

Prior to the new update, I could size an image by changing the number 𝑛 in ![[image.png|𝑛]]. But now I can’t seem to view that text instead of the actual image. I can only drag the corner of the image to resize it, which isn’t what I want.

You used to be able backspace until your text cursor was adjacent to the image embed and it would should you the text instead of the image, but this is no longer the case with the new update.

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u/BDady — 1 day ago
▲ 2 r/mw3

Is it normal for all weapon attachments to be unlocked?

Haven’t played since early-mid 2010s. Just got IW5 and started playing again. When creating a class, I noticed I can choose any weapon attachment, even with weapon level 1.

This isn’t normal right? I even reset my stats and I still have access to all weapon attachments.

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u/BDady — 14 days ago
▲ 20 r/CFD

Why is Delta t / 2 in the denominator of the finite difference approximations of the time derivatives?

This is from Hoffman's CFD Volume I. As part of Problem 3.7, I was coding the fractional step method in Python. Problems 3.5 and 3.6 require you to solve the same problem, but with the FTCS and ADI schemes, respectively. I noticed the results from FSM differed significantly from the FTCS and ADI results. When compared to ADI, FSM yields peak percent error of ~100% and is distributed all throughout the wall.

When I changed the Delta t / 2 to just Delta t, the results of FSM were significantly closer to that of FTCS and ADI. When compared to ADI, percent errors peak around 10% and is limited to small regions near the left/right walls.

The only other textbook I could find that has a section on the FSM was Chung's CFD book, which also has Delta t / 2 in the denominator. However, Hoffman and Chung's sections on the FSM are almost identical (compare the first image with the last), and I don't think they can be considered independent resources.

Is there a mistake in their equations, or is it likely that there is an error in my code.

u/BDady — 1 month ago
▲ 18 r/reptiles

Is this a male or female?

Trying to figure out if this lizard is a boy or a girl. I know these pictures aren’t ideal for such a determination, but I don’t want to handle the lizard to get better photos.

Today there was another Texas spiny lizard in this lizard’s hangout spot, and he/she was NOT happy about it. They were in a hunched position and doing lots of pushups. This allowed me to get a decent picture of its underbelly. Seems there are no blue scales. Does this mean it’s a girl?

u/BDady — 2 months ago
▲ 5 r/FluidMechanics

Is the flow deflection angle through the oblique wave the same as the flow deflection angle through the expansion fan?

I am trying to solve Problem 5.15 of John Anderson's Modern Compressible Flow. My approach to the problem is quite different from two Chegg solutions I have viewed, and the difference in our answers is a little more than 8%.

In trying to understand where the source of the error comes from, I noticed that both Chegg solutions assume the flow deflection through the oblique shock is the same as the flow deflection through the expansion fan. Is this really the case, or is their assumption false?

I have attached a link that includes the problem prompt for Problem 5.15, my solution, and the methodology of the Chegg solution. Could someone shed some light on whether I'm wrong or not? It would be sincerely appreciated.

Edit: I forgot to include the tabulated data I am using. The tables can be found here: Tabulated data (Google Drive link)

u/BDady — 3 months ago
▲ 7 r/aerodynamics

Anderson’s Introduction to Flight vs. Fundamentals of Aerodynamics

I’m looking for a comparison between two of John Anderson Jr’s books, preferably from someone who has read them.

  1. Introduction to Flight
  2. Fundamentals of Aerodynamics

Would you recommend reading the first before the second?

To give you a better idea of where I’m at in my studies of fluid dynamics and aerodynamics, below is a list of material I have already read:

- Munson’s Fundamentals of Fluid Mechanics: Chapters 1-6, 8 & 11
- Anderson’s Modern Compressible Flow: Chapters 1-6, 8, 9, 11 & 16
- Anderson’s Fundamentals of Aerodynamics: Chapters 1, 3 & 4

I did find what I read of Anderson’s Fundamentals of Aerodynamics to be tough material, I definitely don’t have a strong grasp on it and I need to review it. But right now, I’m wondering if it’s worth giving Introduction to Flight a read.

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u/BDady — 3 months ago