advancing interfacial flow simulations in openfoams3-eu-west-1.amazonaws.com ›...

Advancing interfacial flow

simulations in OpenFOAM

Johan Rønby

DANSIS seminar

Computational Techniques for Gas-Liquid Flows,

May 16, 2018

Artificial surf reef in Australia Offshore wind turbines in Denmark

OpenFOAM for interfacial flow simulations at DHI

#3

The Volume-of-Fluid (VOF) method

Cell volume fractions: 0 ≤ 𝛼𝑖 ≤ 1Video link

Interface advection in OpenFOAM/interFoam

Algebraic VOF method:

Interface compression

with MULES limiter

Not shape preserving!

Do alternatives exist?

Geometric VOF methods

Complex and expensive

#4

Simple pure advection test:

Circle in constant flow

Video link

#5

isoAdvector: a new geometric VOF method

Novelty:

1.

Interface reconstruction

based on isosurfaces

2.

Interface advection/

VOF fluxing step

based on geometric

plane-polygon

intersection.

More conceptual details in Roenby, Bredmose and Jasak, Royal Society Open Science 3: 160405

Video link

#6

Circular disc in constant flow on hex mesh

dx = Radius/5

CFL = 0.5

Exact solution

0.5 contour

0.01 contour

0.99 contour

isoAdvector MULES

IsoAdvector MULES HRIC CICSAM (0.5)

#7

dx = R/5

dx = R/10

dx = R/2.5

CFL = 0.5

IsoAdvector is slightly

faster than HRIC and

CICSAM, and 2-4 times

faster than MULES

Circular disc in constant flow on hex mesh

#8

IsoAdvector works on unstructured meshes

Pure advection test cases with tetrahedral cells:

Sphere in constant velocity field Sphere in analytical, time-

reversed velocity field

Video link Video link

#9

For coupling to p-U solver see J Roenby, H Bredmose, H Jasak, "IsoAdvector: Geometric VOF on general meshes", 11th OpenFOAM Workshop book (in print)

Coupling isoAdvector with p-U solver

DamBreak case

Video link

Wave propagation

#10

Stream function wave in periodic domain

Depth = 20 m, Wave height = 10 m, wave period = 10 s

From conference paper: Roenby, Larsen, Bredmose & Jasak, "A new volume-of-fluid method in OpenFOAM", MARINE 2017

Surface after 10 periodsExact solution

Square cells

Tall cells

Flat cells

Wave hitting jacket structure

#11 Bjarne Jensen, DHIVideo link

Power plant outfall

#12 Danilo Tomasselli, DHIVideo link

Green water on ship decks

#13

Article link

Fire sprinklers

#14

Article link

Automatic mesh refinement (AMR)

#15

Testing with Erkki Laurila and Ville Vuorinen from Alto University

MULES isoAdvector

Video link

#16 Submitted to International Journal of Multiphase Flow

Original

isoAdvector

reconstruction

New reconstruction method

isoAdvector reconstruction

Submitted to Journal of Computational Physics

Preprint: arxiv.org/abs/1801.05382

• isoAdvector: a new VOF method for general unstructured meshes

• Accuracy: comparable to existing geometric VOF schemes

• Efficiency: similar to fastest algebraic VOF schemes

• Availability: Integrated in OpenFOAM.com version and available

for OpenFOAM.org version on www.github.com/isoAdvector

• Future development: Moving meshes, Automatic mesh refinement,

surface tension, compressible flows, larger time steps, ...

• More info: www.stromning.com/isoAdvector

Summary

Thank you

for your

attention

Video link