Introduction   

My educational and research track records have been in three general areas: Mechanical, Aerospace and Process/Chemical/Environmental Engineering, but in broader terms relate to thermal-fluid sciences (fluid mechanics, heat and mass transfer and thermodynamics), energy systems engineering including renewable energy and waste heat recovery, as well as development of measurement techniques and instrumentation for complex thermal-fluid systems. Some of my current research interests are listed below:   

Thermoacoustic Technologies: These are based on the thermoacoustic effect whereby appropriately phased pressure and velocity oscillations enable the compressible fluid to undergo a thermodynamic cycle (similar to a Stirling cycle) in the vicinity of the solid material. Here an acoustic wave interacts with a porous solid material either to produce acoustic power, induced by a temperature gradient imposed on the solid, or to obtain a temperature gradient along the solid, induced by an imposed acoustic wave. Potential applications of thermoacoustics include heat pumps for domestic applications or upgrading industrial waste heat; direct conversion of waste or geothermal heat or solar power into electricity; liquefaction and re-gasification of natural gas; combined heat and power systems; tri-generation systems (power, heating and cooling); solar driven cooling and air conditioning and many others. Click HERE for more detail.

Thermal-Fluid Processes in Oscillatory Flows: My interests in unsteady flow and heat transfer phenomena in oscillatory flows stem from the area of Thermoacoustic Technologies. However, similar problems exist in Stirling engines and pulsed-tube coolers in cryogenics. Also, enhancement of heat transfer by using oscillatory, and in some cases pulsating, flows is important in many areas of mechanical and chemical engineering for intensification of heat transfer processes and possible miniaturization of heat exchangers of the future. In this respect, I have developed dedicated experimental facilities equipped with laser-based thermal-fluid diagnostics techniques, including Particle Image Velocimetry (PIV) and Planar Laser Induced Fluorescence (PLIF), to measure the time-dependent fluid flow and heat transfer behaviour. In addition to the experimental work, numerical modelling has been carried out using a CFD package Fluent. Some examples of such work are given in PhD theses of my former research students (see examples HERE or HERE) and selected papers (see examples HERE or HERE).

Applied Aerodynamics and Fluid Mechanics: This covers a range of steady and unsteady fluid mechanics problems where on the fundamental level one needs to consider a range of phenomena such as turbulent transition, flow separation and reattachment, generation of vortex structures and their complex interactions as well as their dissipation and breakdown. These types of processes are important in many areas of engineering, including in particular mechanical, aerospace, civil or chemical. Here, the typical examples include the design of wind turbines, investigations of various wing planforms of flying vehicles, automotive-related aerodynamics for energy efficient land-based transportation, urban design, wind loading problems on civil structures, internal flows within buildings, Earth boundary layer problems and weather phenomena, use of vortex structures in enhanced mixing processes and many others. All these are being investigated both experimentally and numerically. An example of the aerospace-related flow control of large-scale vortex structures using injection of small amounts of momentum by using "synthetic jets" can be found HERE.

Multiphase Flows and Processes: This research concerns both experimental and modelling work to enable understanding and prediction of a wide range of industrially relevant flow situations such as gas-solids, solids-liquid and gas-liquid systems, commonly encountered in pneumatic and hydraulic conveying, centrifugal separation, fluidized beds, flows from hoppers and silos, waste water treatment plants or mining plants, as well as liquid-liquid systems such as those present in oil-water separation processes. The fundamental issues addressed here include the dynamics of particle assemblies and their interactions with carrying fluids, particle microstructures and interface phenomena or rheological properties of complex suspensions and poly-dispersed mixtures. This work aims to answer basic technological questions concerning the effects of process parameters on the nature of the multi-phase and multi-component systems and is regarded as vital for designing new processes in the future. An example of studying gas-solids flow structures can be found HERE.

Sensors and Instrumentation for Multiphase Flows/Heterogeneous Mixtures: The development of reliable measurement and sensor techniques in the area of multi-phase and multi-component systems is one of the important research areas. On the fundamental level, it is required as an important means for validating the developed modelling tools. On the practical industrial level it is required for monitoring and control of a range of processes. My research has included for example the use of Electrical Capacitance Tomography (ECT) techniques for measurement of solids mass flow rates in pneumatic conveying (see example HERE). Similarly, I have been working on development of multi-modality thick-film sensors for composition detection of heterogeneous mixtures, which relied on simultaneous use of electrical impedance techniques and ultrasonic time-of-flight (see examples HERE or HERE). Some of the industrially relevant work has been carried out on oil-water interface detection in horizontal oil-water separators commonly found in off-shore and on-shore oil and gas extraction plants (see example HERE).

Thermal and Flow Management in Microfluidic Devices: In general terms, microfluidic devices handle small volumes of fluids (micro-liters, nano-liters). Flows are usually implemented inside channels with characteristic dimensions from tens to hundreds of microns. The applications of microfluidic devices include engineering of "labs-on-chips" for various bio-chemical analyses, manufacture of high-value speciality chemicals or in biotechnology for handling individual cells/particles. Controlling the flow and thermal conditions within such small devices is challenging. My particular interests lie in the application of micro-scale thermoacoustic coolers/heat pumps to precisely control the required temperature differentials and heat fluxes with high spatial accuracy as well as utilization of acoustic streaming phenomena for handling particulate or biological materials within the devices. Mixing processes in microfluidics are also a challenge due to typically low Reynolds numbers. Such "laminar mixing" can be enhanced by application of miniature piezo-ceramic actuators and acoustic excitation.