center of gravity and buoyancy

26 Oct, 2020 09:04 PM

Dear all

I need urgent help.. I'm not a fluid engineer and need to be corrected within my case:

I've designed a swimming-Gliding robot with changing it's COG, now the robot succeeded to dive and float but I need to do my calculations regarding the center of buoyancy and COG..

If the robot is essentially at neutral buoyancy state , then after changing the COG it will pitches down and with the help of the fins it will dive efficiently. And after a predetermined time the COG returns back to its initial position and with the fins propulsion the robot started to float . Now how can I do my calculations regarding COG and COB?

Ananth Narayan

Oct 27, 2020

Suppose to calculate COB, you will have to use this formula: h+(I*(sin@)^2/hA), here h is center of gravity distance from top free surface of water, I is moment of Inertia of the body, @- Angle, if the body is vertical then it is 90 deg.

For stable floating body, Metacenter, COG and COB should lie in same line and must exist in this order. You must be knowing where the COG exists. Now you can calculate distance between COG and COB. Also for determining distance from Metacenter to COG = (I/V)-(Distance between COG to COB)

ANSYS CFD Fluent

Created by Ananth Narayan on 4 September, 2018

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center of gravity and buoyancy