TITLE : Water elevation in an open U-bend

BY : CHAM User Support Team - Dr S V Zhubrin 

FOR : Demonstration case

DATE : November, 2000

PHOENICS Version : 3.3.1

PHYSICAL SITUATION :

• Steady Free Surface Flow of Water in an open channel with U-turn.
• The task is to simulate the velocity distribution along with free water surface elevation.

ASSUMPTIONS :

• Hydrostatic pressure
• Incompressible, homogeneous fluid
• Viscous, bed friction and turbulence effects are neglected
• Non-varying bed topography
• Shallow flow: small vertical scale relative to horizontal
• Well-mixed-in-depth flow: uniform vertical distributions

SHALLOW-WATER MODELLING:

• Two-dimensional treatment of three-dimensional flows with the local depth calculated as part of solution.
• Depth-averaged version of Navier-Stokes equations;
• Equations solved by analogy to isentropic, compressible gas flow:
  • Density, RHO1= Depth, h
  • Pressure, P1= g*h**2/2, i.e.
  • RHO1=sqrt(2*P1/g)
  • U1, V1 = depth-averaged velocity components

NUMERICAL DETAILS :

• BFC computational grid.
• Boundary conditions:
  • Fixed fluxes for inlet mass/momentum and
  • Fixed-pressure outlet (equivalent to fixed depth).

RESULTS :

The plots show the distribution of velocity and water depth (free surface elevation) within the channel.

Pictures are as follows :

• U-bend geometry and grid
• Velocity vectors
• Water depth, m

THE IMPLEMENTATION

All model settings have been made in VR-Editor of PHOENICS 3.3.1.

The relevant Q1 file can be inspectedby clicking here.

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