Force and Moment Coefficients Results Item does not recognize a unit vector for 3 degrees

Project Support
1

It looks to me that due to input data precision errors, I am no longer able to enter a unit vector for 3 degrees (and likely almost any other discrete angular vector value) in the Forces and Moment Coefficient Result Item without being presented with an Error message that prevents simulation runs when my rounded unit vector value is virtually 1 like the example I show below.

The number of significant digits that I am allowed to enter for a 3 degree unit vector lx is 5.234e-2 and lz is 9.986e-1 which comes out to a unitized value of 0.999970717371264, which apparently isn’t close enough to 1 for the error generating code which SimScale currently uses to test if I have input unit vectors properly :frowning:

If I have this issue properly analyzed, can the error checking code be adjusted somehow to fix this, say when the unit vector is within 0.001 of actually being 1 then the error will not be generated.

I am stuck with not being able to run any simulations until I get some help on this.

Thanks
Dale

2

Hey Dale!

Last time I checked the unit vector validation was a little tight. If you use very precise values for sin and cos 3 deg, you should be able to do it.

E.g. the following should work:

  • Sin 3 deg: 0.05233595624
  • Cos 3 deg: 0.99862953475

Cheers

3

Wow, it was really late when I posted because I did not even think of trying 10/11 significant digits, that you suggested, which results in a difference of 0.00000000000472166750142833 and which is CLOSE enough to1.

BUT, if both are 10 significant digits, the difference of 0.0000000000452098358749708 is NOT CLOSE enough to1.

I still say the error checker limits should be loosened.

AND I should have checked that many digits myself, sorry!

Thanks,
Dale

4

How much precise it need to be? recently used a 8 digit and it’s ok.

The calculator I used: https://toolshed.click/scientific-calculator-online

5

Why are you asking? If, as you say, it is ‘OK’ then why does it matter? If you are not getting the expected results and you still get the error message, then simply try using 10 significant digits like @Ricardopg used, and which I also found worked at the time. And you can copy many more significant digits than you need using Windows Calculator app. And I’m sure a Mac has a similar calculator.