Fluid Mechanics: Tank problems.

1. Dec 23, 2015

Ian Limjap

1. The problem statement, all variables and given/known data
In the attached file.

2. Relevant equations
P1/rhoe+v1^2/2+gh1=P2/rhoe+v2^2/2+gh2

3. The attempt at a solution
I do not know how to begin it; however, I think part(iii) is the same as part (iv)

Attached Files:

• tank problems.docx
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2. Dec 24, 2015

SteamKing

Staff Emeritus
Here is the text of the problem, taken from the linked file:

"A well-vented cylindrical tank with a diameter of 4.0m and height 6.0 m is mounted on its axis and is used to store temporarily a process liquor prior to its use. The tank is filled from the top by tanker, and a discharge pipe is attached to the bottom of the tank which feeds to the process. Flow under the influence of gravity and controlled by a manually-operated valve. The tank also features a drain valve at the bottom of the tank which is normally closed and the tank as a sight glass to indicate its depth. The tank is surrounded by a bund wall which measures 6.0 m by 6.0 m.

"(i)If the maximum working depth of the tank is 5.0 m, determine the time to drain the tank through the drain valve if the valve is equivalent to the discharge through an orifice with an effective diameter of 25 mm. Assume a discharge coefficient of 0.6. You should derive any equations used. State all assumptions used.

"(ii)Determine the height of the bund if the bund is to safely contain all the liquor in the event of catastrophic tank failure.

(iii)Should there be damage to the side of the tank resulting in a hole in the side of the tank at some elevation, determine whether the bund would be effective at containing the discharging liquid. Assume the discharge coefficient of a hole is 0.6.

"(iv)If the discharge from the tank is normally through the long length of discharge pipe with a valve, present a material balance equation to express the rate of change of depth with time. You do not need to solve the equation, but instead explain the mathematical complication to solve the equation."

You should be able to calculate the volume of the product in the tank given its diameter and the depth of the fluid inside. You should be able to calculate the answer to part ii) with just a simple knowledge of geometry.

And no, part iv) is not the same as part iii). Ask yourself, 'Why would anyone write duplicate parts in the same problem?'

You can't solve anything if you don't make an effort. Throwing up your hands and saying 'I don't know how to start!' is not sufficient effort.