Description

This project models tank filling (charge) between two same-height reservoirs using ANSYS Fluent. A two-phase VOF approach captures the interaction between water and air, reflecting operations common in chemical processing where phase separation and transfer are key.

Geometry & Mesh

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  Geometry: Two 2D reservoirs, each 1.25 × 2.5 m, built in ANSYS DesignModeler.

  
  


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  Mesh: Structured grid generated in ANSYS Meshing with 32,510 cells.

  
  

Simulation Setup

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  Solver: Pressure-based, transient.

  
  


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  Gravity: −9.81 m/s² along the Y axis.

  
  

Physical Models & Properties

Multiphase (VOF)

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  Phases: 2 (primary air, secondary water)

  
  


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  Interface: Sharp

  
  


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  Formulation: Implicit

  
  

Turbulence

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  Model: Realizable k–ε

  
  


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  Near-wall: Standard wall functions

  
  

Material properties

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  Air: ρ = 1.225 kg/m³, μ = 1.7894×10⁻⁵ kg/(m·s)

  
  


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  Water (liquid): ρ = 998.2 kg/m³, μ = 0.001003 kg/(m·s)

  
  

Boundary Conditions

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  Walls: Stationary wall.

  
  


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  Inlet-vent: 0 Pa gauge pressure.

  
  


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  Outlet-vent: 0 Pa gauge pressure (pressure profile multiplier = 1).

  
  

Numerics

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  Pressure–velocity coupling: Coupled.

  
  


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  Spatial discretization:

  
  
  
  
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    Pressure: PRESTO!

    
    
  
  
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    Momentum: Second-order

    
    
  
  
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    Volume fraction: Compressive

    
    
  
  
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    k, ε: First-order upwind

    
    
  
  
  
  

Initialization & Run

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  Initialization: Standard.

  
  


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  Patch: Water volume fraction = 1 on Surface-body.

  
  


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  Time step: 0.001 s

  
  


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  Max iterations/step: 20

  
  


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  Number of steps: 10,000

  
  

Results

The solution yields 2D contours of volume fraction, pressure, velocity, and turbulent kinetic energy. The animation shows air rising as water advances toward the air-filled tank. After several seconds, the system approaches hydrostatic balance, with equal pressure at equal elevations across the connected reservoirs.