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Fluid Dynamics (FD) Department

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The mission of the Fluid Dynamics (FD) Department is to develop novel computational methods and techniques for various fluid related 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 Flow

Fluid-structure Interaction

Environmental Modeling


Multiphase Flow

The research objective of the Multiphase 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 complex multiphase/interfacial flow physics. It also provides fundamental understanding and effective tools for other studies where multiphase flow is a common existence.

Our research foci 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
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 multiphase flow group has developed a suite of in-house numerical codes using different modelling approaches for various applications, including Front Tracking method, Level-set method, Immersed Boundary method, 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: Particle suspension flow modeling.


Figure 2: Droplet splash dynamics.


Figure 3: Modeling of microfluidics (cell sorting and trapping as shown).


Figure 4: Modeling of bubbly flow.


Fluid-Structure 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 many engineering applications. The aim of this research is to develop advanced computational techniques and models to predict coupled FSI applications with highly effective, accurate, massively scalable performance.

Adequate solvers for fluid and solid mechanics alone are well developed. Challenges arise at the junction of the two fields – where the motion of the fluid and response from solid cannot be decoupled. Simulating such FSI problems need to deal with not only large differences in spatio-temporal scales, but also completely different physical properties of each medium. We have developed advanced methodologies in our group for four main key components: robust flow and structural solvers, coupling algorithms and mesh generation techniques.

At FSI group, we continue to expand the core capabilities in various areas with a stronger emphasis on applying the existing and future development for potential applications with industrial and academic partners. In particular, we will reinforce our strategies and focus the research and development in the following areas:

Marine-Offshore Hydrodynamics
The program focuses on building fundamental capabilities for marine-offshore applications with great interests from various industries and academic. This focus presents a very broad research of multi-scale and multi-physics in nature. In particular, we will aim at the following research topics:
  • Three-dimensional vortex induced vibrations simulations of riser arrays
  • Strong nonlinear hydrodynamics for wave run-up for semi-submersible platform

Figure 5: Simulations of wave impact on spar-buoy floating structure.


CFD-based Risk Analysis

Computational fluid dynamics (CFD) has been used as a reliable tool for risk analysis, consequence study as well as mitigation planning. The current research focuses on building physical models and numerical simulation techniques for pollutant dispersion in urban-scale areas, improvement of blast and explosive impact simulations as well as uncertainty (stochastic) and risk analysis. The main application areas in the current research theme are:
  • Blast/explosion impact prediction and analysis
  • Evaluation, design of protective structure
  • Offshore structure risk analysis (leak, explosion…)

Figure 6:Blast wave propagation in a large scale urban area.(left) Prediction of structure response under the impact of strong blast wave.(right)


Aerodynamics

In this focus, we aim to develop a novel approach for aerodynamics simulations and aeroelasticity using nonlinear FSI analysis. This problem poses several challenges required to address in full detail. In particular, the main research topics in this theme are:
  • Enhancement of lift-drag prediction (DPWs, HiLIFT)
  • Turbulence modelling (LES)
  • Gust load simulations
  • Wind turbine aerodynamics, rotorcraft aerodynamics

Biological Flows
This study aims at building up capabilities for simulations of biological flows for in-vitro diagnostic and design of medical devices. This research is intrinsically multi-disciplinary and requires broad investigations and extensive development. Our particular interests are:
  • Simulations of patient-specific cardiovascular system (including human heart, arteries...) using FSI approach.
  • Development of heart valve simulator assisting valve design and surgery optimizations.

Figure 7:Velocity contours and vectors in human heart left ventricle over one cardiac cycles.


Environmental Modeling

The Environmental Modeling Capability Group’s primary objective is to conduct research and support industry over a myriad of environmental issues, focusing on urban heat island impact, energy efficiency solution and the national green-mark building thrust.

Our environmental modeling adopts a multi-scale, multi-physics approach. It ranges spatially down from urban scale (~10 km), district scale (~1 km), building scale (~100 m), up to indoor/room scale (~10 m) and finally to human scale (~1 m). It also involves thermal storage transfer between the modeling objects and ambient environment, radiation, and thermal transfer. The research integrates multi-disciplinary fields with scientists from CFD, environmental, atmospheric, energy, building engineering, and health care professions.

Our four key research areas are:
  • Urban airflow dynamics
  • Building flow and ventilation
  • Indoor and urban pollutant dispersion
  • Fire dynamics

Our environmental modeling is applied to climate change impact & urban planning analysis, building energy efficiency & integrated design tool, risk analysis & mitigation, air quality & health assessment.

We develop computational algorithms and tools to solve specific environmental applications. Our group works with various government agencies; as well as private companies. Typical projects include air quality modeling, climate change impact, urban CFD, HVAC design, fire and smoke assessment, thermal comfort evaluation studies, public health assessment, biodiversity and water resource management.

Figure 8: Airflow Simulation Software Development for Natural Ventilation Analysis in Green Building Design.


Figure 9: 3D wind mapping for Marina Bay area.


Figure 10: Singapore hawker center ventilation study (temperature distribution).


Dr. Lou Jing
Department Director



This page is last updated at: 21-Aug-2013