Horizontal open channel flow. Hydraulic jump calculation
Horizontal open channel flow. Hydraulic jump calculation
(OP)
Dear Fellow Engineers
I'm having an issues with my calculations. This case concerns a open channel flow that start off being supercritical on the left and turns into subcritical flow after a hydraulic jump.
Given:
Volume flow rate Q = 0.16m^3/s
Width of the channel b = 1m
Resulting fluidheight at the left h1 = +/-6cm.
The channel slope = 0. The channel is perfectly horizontal
Mannings coefficient : 0.012

Question : Distance from the left part untill the hydraulic jump occurs. L = ?
I integrated the backwater function:
i = 0 because of slope being zero

In the figure below the X axis denotes the distance from the left to the right of the channel. the Y-axis shows the height of the fluid height (purpl/pink curve). The blew curve is the conjugate height.

I know that L can be determined from this curve but i don't know how. Can someone halp out please ?
Thank you,
Jochem Grietens
I'm having an issues with my calculations. This case concerns a open channel flow that start off being supercritical on the left and turns into subcritical flow after a hydraulic jump.
Given:
Volume flow rate Q = 0.16m^3/s
Width of the channel b = 1m
Resulting fluidheight at the left h1 = +/-6cm.
The channel slope = 0. The channel is perfectly horizontal
Mannings coefficient : 0.012

Question : Distance from the left part untill the hydraulic jump occurs. L = ?
I integrated the backwater function:
i = 0 because of slope being zero

In the figure below the X axis denotes the distance from the left to the right of the channel. the Y-axis shows the height of the fluid height (purpl/pink curve). The blew curve is the conjugate height.

I know that L can be determined from this curve but i don't know how. Can someone halp out please ?
Thank you,
Jochem Grietens





RE: Horizontal open channel flow. Hydraulic jump calculation
What you may calculate it the Length of the jump. L
See the method in the link:
http://www.tvrl.lth.se/fileadmin/tvrl/files/vvr090...
http://www.google.com/url?sa=t&rct=j&q=&am...
RE: Horizontal open channel flow. Hydraulic jump calculation
Thank you for the very usefull links u provided. I know that there is a way to calculate the length of the jump itself. But what i need is an estimation of the location of the start of the jump.
I have taken a look into the VBA Excell sheet (second link you provided). It depicts and calculates the distance "Lj". It's this value that i would like to be able to calculate. However, when i put my slope S0=0,it gives an error message saying that a devision by zero is taking place.
I find it hard to believe that there is no way to estimate Lj for horizontal channels.
Any input is very welcome.
Regards,
Jochem Grietens
RE: Horizontal open channel flow. Hydraulic jump calculation
The GVF section is not a hydraulic jump, and is analyzed separately from the jump as per the attachment.
The hydraulic jump starts at y1T.
RE: Horizontal open channel flow. Hydraulic jump calculation
Thank you for that info. I am already aware of the different type of approximation GVF and RVF. But do you think it is possible to calculate a estimation of the end of the GVF zone. The pink curve in my original post was calculated using GVF assumptions and intigrating the backwater curve. However, i do not know where this GVF part wil switch into the hydraulic jump.
RE: Horizontal open channel flow. Hydraulic jump calculation
RE: Horizontal open channel flow. Hydraulic jump calculation
RE: Horizontal open channel flow. Hydraulic jump calculation
I have heard about this HEC-RAS software. Would this software be fit to simulate my case ?
I see there are many modules of the software. Which one would be fit for my case do you think ?
Regards,
Jochem
RE: Horizontal open channel flow. Hydraulic jump calculation