Nwebie,formula for drag of submerged object

In summary, a newbie is asking for help in understanding the formula and steps for computing the elements needed for a task involving a submerged styrofoam rectangle with dimensions of H 100cm x L 15cm x W 50cm, submerged at 20 meters (60ft) underwater. They need to calculate the time it will take for the object to surface at the top and its speed, based on the formula for drag. However, there is no exact hand calculation for this and the drag depends on the surface and geometry of the block, which can vary with depth. It is suggested to estimate and experiment with different scenarios. The rectangular block is made of smooth styrofoam and coated with a thin fibreglass film.
  • #1
alibaba2
32
0
hi, newbie needs a little help...what is the formula and could someone please take the time to explain in detail how to compute the elements in the formula for the following task.

a submerged styrofoam rectangle with size H 100cm x L 15cm x W 50 cm. the object is submerged at 20 meters (60ft) underwater. it will be rising upward with the top side (750cm^2 area )
based on formula for drag, i need to calculate how long it will take to surface at the top, and what is its speed.

big thank you in advance...
 
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  • #2
There really no hand calculation for this. You can define buoyancy force using Bernoulli's equation however the drag is rather difficult. It relies on the surface and geometry of the block which can change significantly depending on the depth its rising from. My suggestion is just to guesstimate with experimenting.
 
  • #3
surface of the rectangular block is styrofoam, coated with thin fibreglass film, so it is 100% smooth. shape is defined in the initial text.
10x
 

1. What is the formula for calculating drag on a submerged object?

The formula for drag on a submerged object is given by FD = 0.5 * ρ * v2 * CD * A, where FD is the drag force, ρ is the density of the fluid, v is the velocity of the object, CD is the drag coefficient, and A is the cross-sectional area of the object.

2. How do you determine the drag coefficient for a submerged object?

The drag coefficient for a submerged object depends on various factors such as the shape and size of the object, as well as the properties of the fluid it is moving through. It can be determined experimentally through wind tunnel tests or through numerical simulations using computational fluid dynamics (CFD).

3. Does the density of the fluid affect the drag force on a submerged object?

Yes, the density of the fluid plays a significant role in determining the drag force on a submerged object. A denser fluid will result in a higher drag force, while a less dense fluid will result in a lower drag force.

4. Can the drag force on a submerged object be reduced?

Yes, the drag force on a submerged object can be reduced by altering the shape of the object or by using certain techniques such as streamlining. By reducing the drag force, the object can move through the fluid with less resistance, resulting in improved efficiency and performance.

5. How is the formula for drag on a submerged object different from the formula for drag on a surface object?

The formula for drag on a submerged object takes into account the density of the fluid, while the formula for drag on a surface object does not. Additionally, the drag coefficient for a submerged object may be different from that of a surface object due to the different flow patterns and forces acting on the objects in their respective environments.

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