# Grigson Formula Needed

Discussion in 'Hydrodynamics and Aerodynamics' started by DCockey, Aug 11, 2011.

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### DCockeySenior Member

I'm looking for the Grigson formula for estimating/approximating viscous friction, either a copy of Grigson, C.W.B., A planar friction algorithm and its use in analysing hull resistance, Trans. RINA, 2000, pp. 76-115, or the formula itself.

Use will be to make some comparisons with the ITTC 1957 curve results at relatively low Re.

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### Olavnaval architect

DCockey,

Leo Lazauskas started this very interesting thread some years ago. In his opening post you'll find an attached excel file containing different formulae for cF (ITTC '57, Hughes, Katsui, Grigson, and a formula derived by Leo himself).

All you have to do is to enter a (low) Re of your choice and see what happens...

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### Leo LazauskasSenior Member

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### DCockeySenior Member

Thank you to Olav and Leo. I just re-read the excellent thread Olav referenced but missed that the formulas were in the spreadsheet.

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### DCockeySenior Member

If anyone downloads Leo's spreadsheet from the thread that Olav posted a link for, be aware that you need to use the formula from the correct line depending on Reynolds number for Grigson. The formulas in the spreadsheet change between the lines for Re = 10 million and Re = 100 million. Grigson used two equations and switched from one to the other at Re = 30 million.

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