Calculating force on object being lowered/dropped into water

[PLI]

Any info/resources on calculating the hydrodynamic force on an object when it hits the water surface with constant velocity?

cheers

 

[Simon Bridge]

Welcome to PF.
You mean something like this one or more general like this one?

Put another way - at what level should we be pitching this?
If just lowering an object into water, and at secondary school level, you'd only want to worry about bouyancy and, maybe, surface tension... for eg.

 

[PLI]

thanks simon,

both are good.
trying to get good understanding at "tertiary level", so that i can then put it into a design equation at "secondary school level" :)

haven't had a good read through either yet but I'm ok with submerged buoyancy, drag etc. it's the force acting on the object as it hits the water i need to understand better.

out of interest - do you have drag force and drag coefficient for a square object?

 

[Simon Bridge]

Not lying around no.
These things are not trivial to work out - especially as you'll get turbulent motion.
It's usually easier just to do an experiment.

 

[PJC01]

I would recommend looking into the principles of fluid mechanics and specifically, hydrodynamics. The force on an object being lowered or dropped into water can be calculated using the equation F = ρVg, where ρ is the density of the fluid (water), V is the volume of the object, and g is the acceleration due to gravity. This equation takes into account the buoyant force acting on the object as it enters the water.

To calculate the hydrodynamic force on an object hitting the water surface with constant velocity, you would need to consider the impact force and the drag force. The impact force is the force exerted on the object as it enters the water and is dependent on the velocity and mass of the object. The drag force is the force exerted by the water on the object as it moves through it and is dependent on the velocity, shape, and size of the object.

There are various resources available online, such as textbooks and research papers, that provide more detailed equations and methods for calculating hydrodynamic forces. Additionally, conducting experiments in a controlled environment can also help in understanding the forces acting on an object in water. I suggest consulting with a fluid mechanics expert or conducting further research to obtain more specific information on your particular scenario.