Momentum Balance across Ejector

Momentum Balance across Ejector - Solve command ambiguity - Messages

#1 Posted: 6/23/2018 2:34:35 AM
usamakhan

usamakhan

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In the attached problem I am having x2 issues. The first thing is that if I assign Mhp to 17 elements & then try to solve (built in command) the array of 100 elements is returned? Secondly using Solve (Maxima) I get the required answer (17 element array) but only the last element has the answer (rest are zero)?

Objective is to plot D1 values for given set of Mhp values

File not found.File not found.
#2 Posted: 6/23/2018 6:21:33 AM
Martin Kraska

Martin Kraska

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There were some issues in your file.
1. your expression MomentumBalance... isn't ready for vector arguments. V[2*Mhp evaluates to the scalar product between two vectors. This probably isn't what you want.
2. The last loop iterates over just one element.
3. Data is constantly overwritten by the last entry.
4. In the first iteration of the loop you overwrite your range of value with the first element.
5. Solve() returns a boolean equation. In order to convert this into an assignent, you can use the substitution function at()

The solution is to provide a separate variable holding the range of values and then iterate Mhp over this range.

If you just want the plot, you can use the Maxima Draw function implicit().

2018-06-23 10_58_44-SMath Studio - [Page1.sm_].png
implicit.sm (136 KiB) downloaded 32 time(s).
Martin Kraska Pre-configured portable distribution of SMath Studio: https://en.smath.info/wiki/SMath%20with%20Plugins.ashx
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frapuano 6/23/2018 2:29:00 PM
#3 Posted: 6/23/2018 9:21:58 AM
Вячеслав Мезенцев

Вячеслав Мезенцев

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2018-06-23_17-20-53.png

MomentumBalance.sm (4 KiB) downloaded 30 time(s).
MomentumBalance.pdf (16 KiB) downloaded 37 time(s).
Russia ☭ forever, Viacheslav N. Mezentsev
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frapuano 6/23/2018 2:29:00 PM
#4 Posted: 6/23/2018 1:37:01 PM
usamakhan

usamakhan

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Wrote

5. Solve() returns a boolean equation. In order to convert this into an assignent, you can use the substitution function at()



:d thanks for this marvelous explanation. However I failed to comprehend why the built in solve command returns 100 elements array? Doesn't it work similarly to Maxima Solve?

uni, thanks but how do I dynamically convert the expression MomentumBalance to the one you have used to plot. I mean I cannot find something like this which will result in the right construct to be used by XYPlot

f(x,y):= RHS(expr) - LHS(expr)

#5 Posted: 6/23/2018 2:11:58 PM
Вячеслав Мезенцев

Вячеслав Мезенцев

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Try this.

implicit1.sm (15 KiB) downloaded 35 time(s).
implicit1.pdf (26 KiB) downloaded 44 time(s).
Russia ☭ forever, Viacheslav N. Mezentsev
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frapuano 6/23/2018 2:29:00 PM
#6 Posted: 6/24/2018 10:18:11 AM
Jean Giraud

Jean Giraud

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Wrote

thanks for this marvelous explanation. However I failed to comprehend why the built in solve command returns 100 elements array? Doesn't it work similarly to Maxima Solve?

uni, thanks but how do I dynamically convert the expression MomentumBalance to the one you have used to plot. I mean I cannot find something like this which will result in the right construct to be used by XYPlot

f(x,y):= RHS(expr) - LHS(expr)



1. Once you have Ejector in the two variables, recast as Uni did
2. Solve for an analytical solution ... via Maple
3. Recast/export

Ejector.PNG

Project Solve Ejector [Maple].sm (8 KiB) downloaded 33 time(s).
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