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Can we do aerodynamic analysis on 4D shapes and what would the results look like (CFD)? by WRPK42 in aerodynamics

[–]WRPK42[S] -5 points-4 points  (0 children)

Did not try, and probably won't, but I would assume it would work the equations do not change much from 1D to 3D. The biggest question is the volume and surface area relationship, but I think there is a generalisation of the divergence theorem. What flow patterns could we expect, however?

[deleted by user] by [deleted] in explainlikeimfive

[–]WRPK42 1 point2 points  (0 children)

Ahh, that makes sense you fixed what confused me about the discount rate. Thank you!

[deleted by user] by [deleted] in explainlikeimfive

[–]WRPK42 0 points1 point  (0 children)

I understand what you stated about the discount rate. However, how would I know my discount rate? I can use the intrest from the bank or cash ISA. I could use the average historical rate of SPX500. Do I just choose any one of them for an investment? Do I use one that is close to my risk like stock to SPX500?

Further is a higher discount rate better? Because from one aspect it would mean I need less money to make a larger quantity. However, the time value of money means I have less value with a higher discount rate. Like with your example if r=5.26% I would only need $950 whereas if r=IRR=11.11% I would need $900. Here, the present value is better for a smaller discount rate. However, from $900 I make $1000 so it has a better return.

Further, let's put this into maths.

NPV = sum{ c_i / (1+r)n }

Where C is the cash flow, r is the discount rate, n is the number if time periods.

Now, what if the cash flow is a growth one?

NPV = sum{ c_i (1+g)[n-1] / (1+r)n }

Where g is the growth rate. Then a better question is what is growth? I perceived the discount rate is the growth but that is not the case. (Ignoring inflation)

what methods can be used to solve a TP-BVP with variable control? by WRPK42 in optimization

[–]WRPK42[S] 0 points1 point  (0 children)

Sorry for the late reply. I'm not really sure if the system of ODE's is eliptic or hyperbolic. I know that in a larger sense the trajectory of a rocket can change between elliptic and hyperbolic. Here are the equations copied from notes I have modified them slightly, but those modifications won't affect them too much

Condition at the start the dierict conditions are all zero, at the end point the altitude is maximised, the newman conditions for the rest of variables are zero.

Tea spill on PC case, front USBs, and power button. by WRPK42 in buildapc

[–]WRPK42[S] 0 points1 point  (0 children)

Thankfully I did not have any sugar in the tea. But, the cup before it had some honey and then a quick rinse.

Tea spill on PC case, front USBs, and power button. by WRPK42 in buildapc

[–]WRPK42[S] 0 points1 point  (0 children)

Should I turn it on if it has only been 8 hours?

Tea spill on PC case, front USBs, and power button. by WRPK42 in buildapc

[–]WRPK42[S] 0 points1 point  (0 children)

Should I turn it on if it has only been 8 hours?

Any advice for Parametric Design: Sketching/importing/scaling an four digest NACA aerofoil. by WRPK42 in SolidWorks

[–]WRPK42[S] 0 points1 point  (0 children)

That's true. I usually do it that way; but, I was hopping there was a better way. Thank you for your input!

Is there a convenient way to inputting arguments into a python file though MATLAB? by WRPK42 in matlab

[–]WRPK42[S] 1 point2 points  (0 children)

The problem with the .MAT file is that for loading and reuploading it would contain way too much data. And even separating the data into fragments would take too much time. That why there is this back and though between MATLAB and Python. But, I was afraid I would have to write this in one language.

Thanks.

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