Spillway symulation

Ghirghidov · May 13, 2009, 10:46

I solve a problem - a sloping spillway. The grid consists cubes and therefore spillway looks as a stairway. Is it possible to exclude this effect from simulations

Thanks a lot.

otd · May 13, 2009, 20:34

Make your mesh slope by rotating the gravity vector.

The bed of your channel should be 0 < x < L. The bed is tilted at an angle Q from horizontal and lies along the y = 0 line (x axis). The gravity vector G = abs(G)cosQ + abs(G)sinQ. Make sure your signs are all OK - this is written pretty sloppy.

Good luck.

Ghirghidov · May 15, 2009, 03:22

I am not sure I understand the F3D possibility right. Does this mean I have to rotate spillway, topography and water also?

otd · May 15, 2009, 09:33

The equations you're solving can be expressed in a variety of coordinate systems. It seems to me that system you need is for the x axis to coincide with the bottom of your spillway and the y axis to be perpendicular to the bottom of the spillway. In this system, your solid boundary coincides with the x axis (y = 0) and your boundary has no staggered blocks in it.

You pick the system - that is, you "tilt" the spillway by changing the orientation of the gravity vector relative to the coordinate system.

The gravity vector has two components. The x component in your new coordinate system points along the main flow direction - it drives the flow. The y component is no longer "straight down" but is perpendicular to the bottom of your spillway.

The solution flow-3d calculates, u, v, p, is in the tilted system. The symbols don't change, they just need to be interpreted in the tilted system.

You might ask the flow science support desk about this as well.

May 13, 2009, 10:46	Spillway symulation	#1
Ghirghidov Member Armen A. Ghirghidov Join Date: Mar 2009 Posts: 50 Rep Power: 17	I solve a problem - a sloping spillway. The grid consists cubes and therefore spillway looks as a stairway. Is it possible to exclude this effect from simulations Thanks a lot.

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May 13, 2009, 20:34		#2
otd Member private Join Date: Mar 2009 Posts: 74 Rep Power: 17	Make your mesh slope by rotating the gravity vector. The bed of your channel should be 0 < x < L. The bed is tilted at an angle Q from horizontal and lies along the y = 0 line (x axis). The gravity vector G = abs(G)cosQ + abs(G)sinQ. Make sure your signs are all OK - this is written pretty sloppy. Good luck.

May 15, 2009, 03:22		#3
Ghirghidov Member Armen A. Ghirghidov Join Date: Mar 2009 Posts: 50 Rep Power: 17	I am not sure I understand the F3D possibility right. Does this mean I have to rotate spillway, topography and water also?

May 15, 2009, 09:33		#4
otd Member private Join Date: Mar 2009 Posts: 74 Rep Power: 17	The equations you're solving can be expressed in a variety of coordinate systems. It seems to me that system you need is for the x axis to coincide with the bottom of your spillway and the y axis to be perpendicular to the bottom of the spillway. In this system, your solid boundary coincides with the x axis (y = 0) and your boundary has no staggered blocks in it. You pick the system - that is, you "tilt" the spillway by changing the orientation of the gravity vector relative to the coordinate system. The gravity vector has two components. The x component in your new coordinate system points along the main flow direction - it drives the flow. The y component is no longer "straight down" but is perpendicular to the bottom of your spillway. The solution flow-3d calculates, u, v, p, is in the tilted system. The symbols don't change, they just need to be interpreted in the tilted system. You might ask the flow science support desk about this as well.