# Archer

## OBJECTIVE: Liquid/Gaz Interface Simulations

Describe the interface motion precisely Level Set Method

Handle jump conditions at the interface without artificial smoothing Ghost Fluid Method

Respect mass conservation VOF Method

Solve incompressible Navier Stokes equations Projection Method

Archer is a 3D incompressible Navier Stokes solver with Level Set-Ghost Fluid-VOF coupling and MPI parallelization

## NUMERICS

• Cartesian mesh
• Mac grid (velocities on cell boundaries)
• WENO 5 scheme for convective terms, Adams Bashforth or RK3 or split algorithm in time
• Multigrid algorith for preconditionning Conjugate Gradient Method in Poisson equation solver
• Ghost Fluid method for variable discontinuities at the interface
• CLSVOF for mass conservation
• MPI parallelization

## UNDER DEVELOPMENT

• Immersed boundaries
• Coupling with Lagrangian solver
• New convection scheme (modified Rudman's method)

## GALLERY

### Turbulent jet

Diesel type Jet Atomization : Diameter: 100µm, Liquid velocity 100 ms-1, Turbulence 5%, gas velocity: 0 ms-1, ${\displaystyle \rho _{liq}}$=696 kgm-3, ${\displaystyle \rho _{gas}}$=25 kgm-3

${\displaystyle \mu _{liq}}$ =1.210-3kgm-1s-1, ${\displaystyle \mu _{gas}}$=10-5kgm-1s-1, ${\displaystyle \sigma }$=0.06Nm-1 Numerical simulation by coupling Level Set / VOF / Ghost fluid methods

Mesh : 256x256x2048 (130 millions points) MPI parallelization 128 procs.

### Triple disk injector

• Coupling between internal flow simulations and DNS of primary breakup
• Radius of the jet exit: 90 microns
• Mesh 256x1024x1024 (~270 millions) dx~1.44 micron
• ~3000 nodes on the (half) jet exit
• 2048 procs
• Triple.avi

### Liquid/Gas mixing layer

• Air/water mixing layer
• 30m/s in air, 0.3 in water
• Grid is 512x512x1024 nodes
• Mesh size equals 48 µm.
• 2048 procs, 20 hours for 3500 time steps; Simulation on 70000 time steps, dt~=10-6 s

### Air assisted atomization

• Air/water Jet « Marmottant »
• Ugas=35m/s and Uliq=0.2m/s
• ${\displaystyle \rho _{gas}}$=1,2 kg/m3 ${\displaystyle \rho _{liq}}$ =1000 kg/m3
• Lx=45.6mm (4mm+1.7mm)x8 that is 4 the « jet +gas » diameter
• Grid: 256x256x256,(512x512x512 for level set and VOF, mesh is 90µm)
• 4096 procs on Curie, 12h wall-clock for 25000 time steps.
• Simulation is 250000 time steps.