# Function With While Loop Help

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Brian Peoples on 16 Feb 2019
Commented: Brian Peoples on 18 Feb 2019
Hello--
So I need to calculate time, flow rate, height, and velocity of water exiting a cylindrical container until the container is empty. I must use a while loop within a function to do so. I am supposed to break the loop once h (height) is slightly larger than 0 so h>0. I need to define a counting variable and start at t = 0.
This is my code for the function so far:
function [Q,h,t,V] = hw4_func_BDP(Initial_Height,Outer_D,Inner_D)
p = 1000; %(kg/m^3) pressure of water
g = 9.81; %(m/s^2) acceleration due to gravity
k = ((d^2)/(D^2))*sqrt(2*g); %constant with diameters of large hole vs exit hole
%Outputs (all vectors)
t = 0 %Time
h = sqrt(h0-.5*k.*t).^2 %Fluid Height
V = sqrt(2*g.*h) %Velocity
Q = pi*(Inner_D/2)^2 .*V %Flow Rate
j = 1
while h > 0
%I am uncertain what to do here
j = j+1
end
The inputs in my script are:
h0 = 2; %initial height
D = 1; %outer diameter
d = .1; %inner diameter
Also, I am supposed to calculate these as vectors, should I define them in my script as blank vectors before hand? Like t = [] h = [] V = [] Q = []

Walter Roberson on 17 Feb 2019
At each step, you can determine h (height) by knowing the current volume remaining and knowing the cross-section area of the vessel. At each step, the volume reduces by the flow rate multiplied by the time step.
Brian Peoples on 18 Feb 2019
Oh and the question says we can assume pressure on the top and the bottom is 0Pa

Brian Peoples on 18 Feb 2019
Brian Peoples on 18 Feb 2019
So I am asking about e. on the third page. I can't figure this out.....