rtymea14 / cvofls-dpd

Coupled Volume of Fluid, Level Set and Dissipative Particle Dynamics Solver

CVOFLS-DPD

Coupled Volume of Fluid, Level Set and Dissipative Particle Dynamics Solver

Lead developer: Raihan Tayeb, Doctoral Candidate, University of Missouri-Columbia

Overview

A software for mesoscopic simulation developed using open-sourced softwares, OpenFOAM, OpenSMOKE++, LIGGGHTS and CFDEM

It is employed to investigate the evaporation induced self-assembly of charged polymeric nanoparticles in microdroplet solution

The software can handle

• Complex geometric configuration
• Moving mesh
• Spurious current reduction
• Contact line pinning
• Multi-component liquids (and gases) with mixing and phase change (evaporation and condensation)
• Chemkin style property tables
• Fluid-particle interaction (including fluid interface forces on particles)
• Particle-particle interaction (including DLVO forces and friction force)
• Heat transfers between particles and between particles and fluids
• Parallel processing

If you use this solver in a project or scholarly work, please include the following citation, Tayeb and Zhang (2021).

Installation

The current version of the code uses the OpenFOAM 2.3.1 libraries. It uses isoadvector library for interface tarcking and adection. It also calculates the thermodynamics and transport properties of gases (diffusion coefficients, thermal conductivity, heat capacities, and viscosity) based on the correlations available in the OpenSMOKE++ library. The coupling with the particle solver which is LIGGGHTS is done using CFDEM library. Once all the libraries are installed, you can proceed to install the CVOFLSDPD solver.

To Install: Navigate to a working folder in a shell terminal, clone the git code repository, and build.

$ git clone https://github.com/rtyme14/CVOFLS-DPD.git CVOFLS-DPD
$ cd CVOFLS-DPD/CVOFLS-DPD
$ source Allwmake.sh

The solver can be validated using the case in the validation_case. The nanoparticle-fluid case is in the colloid_case.

Microgravity droplet evaporation case (validation_case)

This case demonstrates evaporation of a spherical micro-droplet,hanging from a thread, in ambient air. The gravity is ignored. Temperature of droplet continues to drop until it reaches wet bulb temperature. Except for a small initial phase, the dimensionless squared diameter follows the linear D2 law. More in the paper.

To run the case do the following

$ comment out the particle coupling part in CVOFLSDPD.C file
$ wclean && wmake
$ cd ../../validation_case
$ blockMesh
$ setFields
$ decomposePar -force
$ mpirun -np ${no. of processors} CVOFLSDPD -parallel

Nanoparticle self-assembly case (colloid_case)

The self-assembly of nanoparticles inside a liquid micro-droplet is studied using the CVOFLSDPD solver. Be sure to uncomment the particle coupling part and recompile, if it is commented out in the validation case. There are two folders for the case. The CFD folder has 0, constant, system and newdir just like other case. The DEM folder has in.colloid file which initializes and solve the particle trajectories. The Sphere2370FromDump.csv file containes the initial coordinates for the 2370 nanoparticles. The case can be run in the same way as before using decomposePar -force && mpirun -np ${no. of processors} CVOFLSDPD -parallel commands. During simulation, a liggghts.restart file will appear which can be used to restart the simulation. This file should be tranferred to the DEM folder and in in.colloid file the read_data command should be commented out and read_restart should be uncommented.

The DPD simulation requires much smaller time steps than the CFD process. The time step for the DPD case is 1×10-9 s whereas the time step for the CFD case is 1×10-7 s which means that for each CFD iteration DPD runs for 100 iterations.

The pinned contact angle evaporation and the colloid deposition for three contact angles are shown in the figure below.

The following videos show colloid deposition for 90 degree contact angle.

Algorithm

An overview of the algorithm used in CVOFLS-DPD solver is given below.

Contribute

Open to collaboration with other investigators studying phase-change and multiscale particle-fluid flows. Please contact us if you are interested in expanding the solver or find bugs to correct. Limited support (on a case-by-case basis) or consulting servies can also be provided.

Acknowledgements

This research was generously supported by the U.S. National Science Foundation.

References

• Tayeb, R, Zhang, Y. "Controlling Evaporation Induced Self-Assembly of Polymeric Nanoparticles: A VOF-DPD Study." Proceedings of the ASME 2019 International Mechanical Engineering Congress and Exposition. Volume 8: Heat Transfer and Thermal Engineering. Salt Lake City, Utah, USA. November 11–14, 2019. V008T09A083. ASME.
• Tayeb, R, Zhang, Y. "Evaporation induced self-assembly of rough colloids: a multiscale simulation study." International Journal of Heat and Mass Transfer. Volume 179, 2021, Article 121681.