Siphon Simulation, Ansys Fluent Training

4.5 (2 reviews)


In this project, a siphon has been simulated and the results of this simulation have been investigated.

This product includes Geometry & Mesh file and a comprehensive Training Movie.
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Siphon Project Description

Water always flows from an area under higher pressure to an area of lower pressure. The siphon effect takes place when the fluid flows to the highest portion of the bend pipe due to the pressure difference and then comes down from there due to the presence of gravity.


In this project, a Numerical simulation of a siphon has been done by Ansys Fluent software. The VOF model has been used to simulate and solve the two-phase flow field equations. The flash tank discharges and the siphoning effect causes the water to drain.

Geometry & Mesh

The 2-D geometry of the present model is generated using SpaceClaim software.


The meshing of the present model has been done using Ansys Meshing software. The mesh type is unstructured in all of the computational domains, and the element number is equal to 95,451.


Siphon CFD Simulation Settings

We consider several assumptions to simulate the present model:

  1. Due to the incompressibility of the flow, the pressure-based solver method has been selected.
  2. The simulation is transient.
  3. The gravity effect is considered equal to -9.81 m.s-2  on Y-axis

The K-epsilon Realizable viscous model with scalable wall function has been used to solve the turbulent flow equations. The pressure-velocity coupling scheme is SIMPLE. The second-order upwind discretization method has been used for Momentum, and the first-order upwind discretization method has been used for Turbulent kinetic energy and Turbulent dissipation rate.

The boundary conditions and their details are shown in the figure below.


The following tables represent a summary of the defining steps of the problem in this project and its solution:

Homogeneous model Volume of fluid
Number of Eulerian phases 2(air & water)
Interface modeling Sharp
Formulation Explicit
Primary phase air
Secondary phase water
k-epsilon Realizable
Near wall treatment Scalable wall functions
Material Properties
Density 1.225
viscosity 1.7894e-05
Density 998.2
viscosity 0.001003
Cell zone conditions
Operation conditions
Operating density method User-input
Operating density 1.225
Boundary conditions
Free surface Pressure inlet
Outlet Pressure outlet
Pressure-Velocity Coupling SIMPLE
Pressure PRESTO
Momentum Second-order upwind
Turbulent kinetic energy First-order upwind
Turbulent dissipation rate First-order upwind
Volume fraction Compressive
Initialization methods Standard (from the free surface)
Patch Phase water
  Variable Volume Fraction
Zones to patch water
Value 1
Run calculation
Time step size 0.002
Max iterations/time step 20
Number of time steps 3500


After the solution process is completed, contours of velocity, Pressure, water volume fraction, and streamline are extracted and presented below. As can be observed, the water inside the flash tank discharges and cause the siphoning effect. Due to the siphoning effect, water will pass through the pipe and go to the highest point, and then due to the action of gravity, it will come downward. Once the water flow has begun, the water will continue to flow, draining the ponding water area off.

You can obtain Geometry & Mesh file and a comprehensive Training Movie that presents how to solve the problem and extract all desired results.


2 reviews for Siphon Simulation, Ansys Fluent Training

  1. Laurits M.

    It has a simple principle, but we use it every day. That is the interesting point!

  2. Dieter

    Hello MR-CFD. Why did you use the Explicit formulation for the VOF model?

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