uu.seUppsala University Publications
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
A fast massively parallel two-phase flow solver for microfluidic chip simulation
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Scientific Computing. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Numerical Analysis.
2017 (English)In: The international journal of high performance computing applications, ISSN 1094-3420, E-ISSN 1741-2846, Vol. 31Article in journal (Refereed) Epub ahead of print
Place, publisher, year, edition, pages
2017. Vol. 31
National Category
Computer Science Computational Mathematics
Identifiers
URN: urn:nbn:se:uu:diva-266273DOI: 10.1177/1094342016671790OAI: oai:DiVA.org:uu-266273DiVA: diva2:867644
Projects
eSSENCE
Available from: 2016-10-05 Created: 2015-11-05 Last updated: 2017-12-01Bibliographically approved
In thesis
1. Towards accurate modeling of moving contact lines
Open this publication in new window or tab >>Towards accurate modeling of moving contact lines
2015 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The present thesis treats the numerical simulation of immiscible incompressible two-phase flows with moving contact lines. The conventional Navier–Stokes equations combined with a no-slip boundary condition leads to a non-integrable stress singularity at the contact line. The singularity in the model can be avoided by allowing the contact line to slip. Implementing slip conditions in an accurate way is not straight-forward and different regularization techniques exist where ad-hoc procedures are common. This thesis presents the first steps in developing the macroscopic part of an accurate multiscale model for a moving contact line problem in two space dimensions. It is assumed that a micro model has been used to determine a relation between the contact angle and the contact line velocity. An intermediate region is introduced where an analytical expression for the velocity field exists, assuming the solid wall is perfectly flat. This expression is used to implement boundary conditions for the moving contact line, at the macroscopic scale, along a fictitious boundary located a small distance away from the physical boundary. Model problems where the shape of the interface is constant throughout the simulation are introduced. For these problems, experiments show that the errors in the resulting contact line velocities converge with the grid size h at a rate of convergence p ≈ 2. Further, an analytical expression for the velocity field in the intermediate region for the case with a curved solid wall is derived. The derivation is based on perturbation analysis.

Place, publisher, year, edition, pages
Uppsala University, 2015
Series
Information technology licentiate theses: Licentiate theses from the Department of Information Technology, ISSN 1404-5117 ; 2015-006
National Category
Computational Mathematics
Research subject
Scientific Computing with specialization in Numerical Analysis
Identifiers
urn:nbn:se:uu:diva-266274 (URN)
Supervisors
Projects
eSSENCE
Available from: 2015-10-26 Created: 2015-11-05 Last updated: 2017-08-31Bibliographically approved
2. Modelling of Moving Contact Lines in Two-Phase Flows
Open this publication in new window or tab >>Modelling of Moving Contact Lines in Two-Phase Flows
2017 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Moving contact line problems appear in many natural and industrial processes. A contact line is formed where the interface between two immiscible fluids meets a solid wall. Examples from everyday life include raindrops falling on a window and water bugs resting on water surfaces. In many cases the dynamics of the contact line affects the overall behavior of the system. Industrial applications where the contact line behavior is important include gas and oil recovery in porous media, lubrication, inkjet printing and microfluidics. Computer simulations are fundamental tools to understand and predict the behavior.  

In this thesis we look at numerical simulations of dynamic contact line problems. Despite their importance, the physics of moving contact lines is poorly understood. The standard Navier-Stokes equations together with the conventional no-slip boundary condition predicts a singularity in the shear stresses at the contact line. Atomistic processes at the contact line come into play, and it is necessary to include these processes in the model to resolve the singularity. In the case of capillary driven flows for example, it has been observed that the microscopic contact line dynamics has a large impact on the overall macroscopic flow.

In Paper I we present a new multiscale model for numerical simulation of flow of two immiscible and incompressible fluids in the presence of moving contact points (i.e. two-dimensional problems). The paper presents a new boundary methodology based on combining a relation between the apparent contact angle and the contact point velocity, and a similarity solution for Stokes flow at a planar interface (the analytic Huh and Scriven velocity). The relation between the angle and the velocity is determined by performing separate microscopic simulations.

The classical Huh and Scriven solution is only valid for flow over flat walls. In Paper II we use perturbation analysis to extend the solution to flow over curved walls. Paper III presents the parallel finite element solver that is used to perform the numerical experiments presented in this thesis. Finally, the new multiscale model (presented in Paper I) is applied to a relevant microfluidic research problem in Paper IV. For this problem it is very important to have a model that accurately takes the atomistic effects at contact lines into account.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2017. 33 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1559
Keyword
Computational fluid dynamics, Two-phase flow, Contact lines
National Category
Computational Mathematics
Research subject
Scientific Computing
Identifiers
urn:nbn:se:uu:diva-329059 (URN)978-91-513-0071-9 (ISBN)
Public defence
2017-10-27, ITC 2446, Lägerhyddsvägen 2, Uppsala, 10:15 (English)
Opponent
Supervisors
Available from: 2017-10-05 Created: 2017-09-10 Last updated: 2017-10-18Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full text

Authority records BETA

Kronbichler, MartinDiagne, AbabacarHolmgren, Hanna

Search in DiVA

By author/editor
Kronbichler, MartinDiagne, AbabacarHolmgren, Hanna
By organisation
Division of Scientific ComputingNumerical Analysis
In the same journal
The international journal of high performance computing applications
Computer ScienceComputational Mathematics

Search outside of DiVA

GoogleGoogle Scholar

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 550 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf