Institute of High Performance Computing
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Research
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Fluid Dynamics (FD) Department
>>Department Members
The mission of the Fluid Dynamics (FD) Department is to develop novel computational methods and techniques for various fluid flow phenomena to help the advancement of Science and Technology, as well as to help industry at large to develop new technological solutions.
The following research areas form the core focus of our Capability Groups:
Multiphase and Interfacial Flows
Fluid-structure Interaction
Environmental Modeling
Biophysics
Multiphase and Interfacial Flows
The research objective of the Multiphase and Interfacial Flow Capability Group is to develop new algorithms and models to solve complex multiphase/interfacial flow dynamics for natural phenomena and industrial processes. These new modeling techniques enable us to investigate significant multiphase/interfacial flow physics. It will also provide fundamental understanding and effective tools for other studies where multiphase flow is a common existence.
Our research focuses are:
- Multi-scale, multi-physics modeling
- Bubble, droplet, particle & fluid flow
- Mass/heat transfer & phase change
- Contact and thin film dynamics
- Microfluidics modeling
- Surface effect & droplet substrate interaction
- Non-Newtonian bubble/droplet flow
There are physical property discontinuities (density, viscosity, pressure) and complex topological changes associated with multiphase/interfacial flow phenomena. Very often, a structure such as membrane or capsule poses extra force on the flow system through immiscible interface where chemical, electrical, bio-reaction, and mass/thermal transfer also occur. The interface topology change and its associated instability also pose a challenge for physical understanding and numerical solution. In this study, we develop high performance computational tools dealing with the inherent numerical challenges to accurately simulate such multiphase/interfacial flow.
The Capability Group has developed a suite of in-house numerical codes using different modelling approaches for various applications, including Front Tracking method, Moving Mesh Interface Tracking method, Immersed Boundary method, Ghost Fluid model, Lattice Boltzmann method, and Boundary Integral method. These modeling tools can be applied to various flow regimes for wide applications from microfluidics, bubble column, boiling, to oil and gas transportation.
Figure 1: Rotating vortex ring (left: experiment; right: LBM simulation result).
Figure 2: Micro-electric jet printing.
Figure 3: Bubble column and bubble interaction.
The Fluid-structure Interaction (FSI) Capability Group focuses on the interaction of movable or deformable structures with an internal or surrounding fluid flow. This interaction has been a crucial consideration in the design of many engineering systems. The aim of this research is to develop computational techniques and models for the accurate prediction of this phenomenon.
Accurate solvers for fluid and solid mechanics are well developed. However, problems arise at the crossroad of the two fields – where the motion of the fluid and solid cannot be decoupled. Simulating FSI problems requires that vast differences in spatio-temporal scales and physical properties of each medium are accounted for. Strong coupling at the interface can result in major problems for computational convergence and efficiency. Our research adopts the loosely coupled methodology that aims to develop a coupled CFD and CSD solver for complex geometry.
The targeted application for FSI includes Aero-elasticity, Blast Simulation and Hemodynamic simulation for Heart Valves.
Figure 4: 2-D Dynamics of flow over flexible Wall.
Figure 5: Aero-elasticity of a T-tailed aircraft.
Figure 6: Blast Simulation.
The Environmental Modeling Capability Group’s primary objective is to conduct research as well as provide support for the industry and nation over a myriad of atmospheric environmental issues.
Environmental modeling is a multi-scale activity. It covers global level climate change, to island level air quality, to street level wind gusts effects on biodiversity, to building level concerns over thermal comfort, and fire and smoke assessment. Environmental modeling is typically applicable to activities such as supporting urban planning, assessment of hazardous gas dispersion, as well as supporting energy-efficient building design.
The four key components that make up the core infrastructure for environmental modeling are Data handling, Models algorithms, Applications & Analysis, and Spatial-Temporal Visualization.
The focus for the Environmental Modeling Capability Group is in computational algorithms designed to solve specific environmental problems, as well as application and analysis. Applications and projects by the Group include: air quality modeling, urban CFD, fire and smoke assessment, thermal comfort evaluation studies, public health assessment, biodiversity and water resource management.
Figure 7: Velocity vectors across an urban landscape.
Figure 8: Coastline spatial visualization.
Figure 9: Gas dispersion past built-up areas.
The Biophysics Capability Group focuses on developing and using theoretical and computational tools to understand the mechanics and biology of proteins, cell, and tissues.
Some sample projects include:
- Theoretical modeling of the mechanical mechanisms involved in lamellipodia-driven mesenchymal cell migration and bleb-driven amoeboid cell migration commonly adopted by tumor cells.
- Large-scale simulation of the migration of a dense suspension of cells in flow using continuum solid and fluid dynamics formulations. Such simulations allow us to accurately compute the rheological properties of, for example, a suspension of red blood cells that may not be easily measured experimentally (See Figure 10).
- Use of atomistic molecular dynamics simulations to understand the regulation of integrin activation, a biological process key to cell adhesion and migration. The physics-based simulations suggested a regulation mechanism for leukocyte integrins, which helped in interpreting experimental data and generating new hypotheses (See Figure 11).
To complement our computational effort, we collaborate with wet labs in A*STAR research institutes, NUS, NTU, and other worldwide laboratories. It is our belief that our modeling and simulations could provide additional quantitative understanding of the mechanisms involved in mechanobiological processes, leading to new forms of therapies or drugs targets that benefit the health of people while boosting the economy.
Figure 10: Computation of Red Blood Cell Migration.
Figure 11: Leukocyte integrins.
Achievements:
- Urban Climate Mapping: Using Computational Fluid Dynamic Tools, researchers from IHPC simulated the air flow pattern over the Singapore CBD/Marina Bay area. The simulation employs suitable turbulence modeling as well as Large Eddy Simulation that able to capture detail flow features around the urban areas. The CFD model developed for the CBD and Marina area was large and complex, IHPC simulation provides good insights for urban planner for pollutants transportation and dispersion consideration.
- Drop Contact and Thin Film Dynamic: The numerical and analytical result of the theory developed by IHPC researchers offers explanation on the coalescence on separation process of bubble droplets. This research was highly recognized by scientists in this area of research. It shed further insights on bubble dynamics.
Dr. Tan Jiak Kwang
Department Director
This page is last updated at: 11-Mar-2012