# Using log function for velocity

**URL:** <https://www.simscale.com/forum/t/using-log-function-for-velocity/36704>\
**Category:** Fluid Flow / CFD\
**Created:** [August 8, 2016, 11:20am UTC](https://www.simscale.com/forum/t/using-log-function-for-velocity/36704 "2016-08-08T11:20:22Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![ajaybharish](https://www.simscale.com/forum/letter_avatar/ajaybharish/32/5_5575768a8748004e209b776fc1b2916d.png) [@ajaybharish](https://www.simscale.com/forum/u/ajaybharish)\
**Post date:** [August 8, 2016, 11:20am UTC](https://www.simscale.com/forum/t/using-log-function-for-velocity/36704/1 "2016-08-08T11:20:22Z")

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Hello,

When I define inlet velocities, I can use several functions like sin, cos, log etc. So here is this log referring to Log-to-base-10 or to-base-e?

I would assume that it is natural logarithm but log-to-base-10 is more commonly used. So I am a bit confused as to what base this is referred to?

Thanks

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**Author:** ![anon18194957](https://www.simscale.com/forum/letter_avatar/anon18194957/32/5_5575768a8748004e209b776fc1b2916d.png) [@anon18194957](https://www.simscale.com/forum/u/anon18194957)\
**Post date:** [August 8, 2016, 11:50am UTC](https://www.simscale.com/forum/t/using-log-function-for-velocity/36704/2 "2016-08-08T11:50:29Z")

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@ajaybharish - thanks for pointing this out, it is not so clear 😖

I believe it is log to base 10 but will need my colleague @anon62721193 to confirm.

Best,  
Anna

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**Author:** ![anon62721193](https://www.simscale.com/forum/letter_avatar/anon62721193/32/5_5575768a8748004e209b776fc1b2916d.png) [@anon62721193](https://www.simscale.com/forum/u/anon62721193)\
**Post date:** [August 8, 2016, 12:25pm UTC](https://www.simscale.com/forum/t/using-log-function-for-velocity/36704/3 "2016-08-08T12:25:49Z")

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@ajaybharish, it’s natural logarithm (base e)

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**Author:** ![anon18194957](https://www.simscale.com/forum/letter_avatar/anon18194957/32/5_5575768a8748004e209b776fc1b2916d.png) [@anon18194957](https://www.simscale.com/forum/u/anon18194957)\
**Post date:** [August 8, 2016, 1:03pm UTC](https://www.simscale.com/forum/t/using-log-function-for-velocity/36704/4 "2016-08-08T13:03:20Z")

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Glad I asked, thanks @anon62721193!

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<div class="post-metadata">

**Author:** ![ajaybharish](https://www.simscale.com/forum/letter_avatar/ajaybharish/32/5_5575768a8748004e209b776fc1b2916d.png) [@ajaybharish](https://www.simscale.com/forum/u/ajaybharish)\
**Post date:** [August 8, 2016, 1:28pm UTC](https://www.simscale.com/forum/t/using-log-function-for-velocity/36704/5 "2016-08-08T13:28:12Z")

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Thanks @anon18194957 & @anon62721193 for the really swift clarification 🙂

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**Author:** ![nl\_victor\_reij](https://www.simscale.com/forum/user_avatar/www.simscale.com/nl_victor_reij/32/58298_2.png) [@nl\_victor\_reij](https://www.simscale.com/forum/u/nl_victor_reij)\
**Post date:** [December 9, 2025, 2:51pm UTC](https://www.simscale.com/forum/t/using-log-function-for-velocity/36704/6 "2025-12-09T14:51:50Z")

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I see the solution here is that the logarithmic function is log10, but I think that the solution is further in the thread,:so it is loge. Correct?

Perhaps alo adjust/extend the text on these pages:

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>
> Formulas allow users to specify a variable or parameter (velocity, temperature, etc.) as a function of other independent variables.

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