filling basin

[Exatem]

Good morning to all the friends of the forum. This time I need an opinion from someone who means plumbing provided that I do not understand a pipe...

I have a bathtub, indeed a basin, say from 20,000m3 dry. is separated from a barrier, a dam, from the water whose height from the bottom to the free fur is more than 7 meters. if in the dam I have 4 openings of 500mm diameter, how long do I fill the basin?
I found numerous formulas, all different from each other.
according to me the filling takes place in three stages. the first goes from 0 until the water has reached the lower level of the openings during which the fall is free. then the condition for which water continues to enter by difference of height, but we are in the presence of a certain reflux since now also the internal water has reached the openings. Finally, when the 4 openings are completely below the level of the internal water, the reflux is even greater and the inlet water slows further until the balance condition is reached.
I do not ask for the solution of the problem and for this I do not indicate the missing data, for example, height of the openings, volume of water without reflux, volume of partial reflux and volume in full reflux.
If someone could tell me a text where finding the solution would be more than enough.
Thank you all.

 

[meccanicamg]

normally all books are very generic and in this case the book treats you as a basin that crosses from the windows of x cmq with a known deltah. you would hardly find the templates as the opening for calculating the localized loss coefficient and you could hardly calculate the turbulent dead. I believe that in these cases very sparing you have to calculate an average speed. otherwise you must simulate it with a cfd.

If you put a box, we better understand who's on it and who's under it.
is certainly a series of stationary states, so you will have to simplify to get something likely

 

[Exatem]

normally all books are very generic and in this case the book treats you as a basin that crosses from the windows of x cmq with a known deltah. you would hardly find the templates as the opening for calculating the localized loss coefficient and you could hardly calculate the turbulent dead. I believe that in these cases very sparing you have to calculate an average speed. otherwise you must simulate it with a cfd.

If you put a box, we better understand who's on it and who's under it.
is certainly a series of stationary states, so you will have to simplify to get something likely

hello mechanicalmg, I counted on you....:finger:
the openings are dn500 butterfly valves, however I found in archive an old calculation report in which are considered the three cases that I have derscribed leaving the variable "n". at the bottom if the basin is filled in 3 hours and 10 rather than in 2 and 58 it does not upset us so much.say that it serves a given that is indicative but not the extreme precision is required.
I do not use the above report because I find numerical values seemingly out of context.
not all the passages are represented and who wrote it must have forgotten something, for example a given "h" appears of which there is no indication of the value.
something I found on the colombo and I will try to deepen.
Monday, I'll put you a pattern for now, thanks to the interest.

 

[meccanicamg]

Okay. We'll update the week that comes. Good weekend.

 

[Exatem]

hello mechanicalmg, I attach you a complete scheme of quotas, meanwhile I try to transcribe how much I found on the texts.

 

[Exatem]

the problem has been solved. the difficulty was in identifying the value of a constant that appeared in formulas but was not indicated anywhere. the solution then was much simpler considering that "g" was nothing but 9,81, acceleration of gravity.
the flow rate has been calculated in three cases with the use of two formulas of which the first is valid in the case of the flow rate relative to the free and partially regurgitated zone, while the second is totally regurgitated.
change in formulas, efflux coefficients for mouths in thin and logical walls, the reference heights.
by curiosity... with 4 dn500 butterfly valves and a height difference of 7,2mt, the 11,500m3 basin fills in 2 hours and 40'.