Designing a gravity-driven fluid flow system

[Urmi Roy]

Basically, I'm designing a simple method in which a small reservoir of water is connected to a narrow pipe and the rate of flow of water changes with changing height of the reservoir.

Now, the water coming out of the narrow pipe is fed into a microchannel.

The resistance is given, by the makers as R (resistance) = 3x10^11 kg/m4s.

1. First of all, what exactly is this quantity (i.e R), since I've never seen the units 'kg/m4s'

2.After that, I obtained the formulae for head loss at entrance of pipe, at the bends etc using formulae given on

http://books.google.co.in/books?id=...frontcover&source=gbs_atb#v=onepage&q&f=false

Chapter 9...all in terms of outlet velocity...so now how do I combine all these things to calculate how the flow through the narrow pipe depends upon the elevation of the reservoir, taking into consideration all these losses?

 

[Valerie Park]

1. The quantity R is the "resistance coefficient" which is a measure of the resistance of the flow in the microchannel. It is usually expressed in terms of kg/m4s and is related to the viscosity of the fluid and the geometry of the channel. 2. To calculate how the flow through the narrow pipe depends upon the elevation of the reservoir, you will need to calculate the pressure drop due to the head loss at entrance of pipe, at the bends etc. You can then use the Bernoulli equation to calculate the velocity of the fluid in the pipe at different elevations. This velocity can then be used to calculate the flow rate in the pipe.