- #1

Panos_leof

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- TL;DR Summary
- Ways to calculate drag coefficient for resistance analysis without knowing drag force and velocity.

Hi there,

I have modeled with MAXSURF a few variations of a prehistoric logboat in order to test a few theories. Now, I am trying to look at resistance-performance over a range of speed. To do so, I need to include a constant drag coefficient without knowing the drag force and velocity (both will be estimated after the resistance analysis).

So, CD = (2*FD)/(ρ*v2*A) is not an option since I am missing FD and V. Also, I cannot solve Cd in terms of the Reynolds number since Re and Cd can relate through velocity.

Is there any other workaround? For now, I just need a constant drag, then I will just use speed^2 and projected area.

Thanks in advance

I have modeled with MAXSURF a few variations of a prehistoric logboat in order to test a few theories. Now, I am trying to look at resistance-performance over a range of speed. To do so, I need to include a constant drag coefficient without knowing the drag force and velocity (both will be estimated after the resistance analysis).

So, CD = (2*FD)/(ρ*v2*A) is not an option since I am missing FD and V. Also, I cannot solve Cd in terms of the Reynolds number since Re and Cd can relate through velocity.

Is there any other workaround? For now, I just need a constant drag, then I will just use speed^2 and projected area.

Thanks in advance