Dr. Suvash C Saha (ড. সুভাষ সাহা)
Dr. Suvash C. Saha is a Senior Lecturer of Mechanical Engineering in the School of Mechanical and Mechatronic Engineering, University of Technology Sydney (UTS), Australia. He received his PhD in Computational Fluid Dynamics from James Cook University, Australia. Then he undertook Postdoctoral training at the Queensland University of Technology, Brisbane, Australia.Dr Saha's current research activities focus on three key areas of (a) Computational Biomechanical Engineering which includes particle deposition, clearance and penetration into the lung surfactant, Red Blood Cell (RBC) deformation into the capillary vessels and aging effect on RBC deformation (b) Heat and Mass Transfer including Phase Change Materials (PCM), Solar thermal energy technology, Natural convection heat transfer in buildings and other confined geometries, Scale analysis for the transient flow, and (c) Microfluidics modelling including inertial separation techniques.
Phone: +61731381413
Address: Postdoctoral Research Fellow
School of Chemistry, Physics and Mechanical Engineering
Queensland University of Technology (QUT), Brisbane, Australia
Phone: +61731381413
Address: Postdoctoral Research Fellow
School of Chemistry, Physics and Mechanical Engineering
Queensland University of Technology (QUT), Brisbane, Australia
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Papers by Dr. Suvash C Saha (ড. সুভাষ সাহা)
weighted residual method of finite element analysis has been used for numerical solution. The code validation and grid independency test have been carried out to justify the numerical accuracy. It has been observed that increment of magnetic field reduces the heat transfer rate, whereas
increment of heater distance augments the heat transfer rate significantly. Results are discussed on the basis of Nusselt number (Nu), Bejan number (Be) and shown by contours and 3D plots. It has also been found that = 0.4 always shows better heat transfer rate and entropy optimization.
Design/Methodology/Approach: Finite volume based CFD software, Fluent (Ansys
15.0) is used to solve the governing equations. Attribution of the various flow parameters of fluid flow and heat transfer are investigated including Rayleigh number (Ra) ranging from 10^4 to 10^6, Prandtl number (Pr) from 10 to 1000, Power law index (n) from 0.6 to 1.4, the cylinder radius (R) from 0 to 0.3, and the angular rotational speed (Ω) from -500 to 500. Grid sensitivity analysis is performed and numerically obtained results have been compared with those results available in the literature and found to be in good agreement.
Findings: Outcomes are reported in terms of isotherms, streamlines and average Nusselt number (𝑁𝑢) of the heated wall for various Ra, Pr, n, R and Ω. Vertical and horizontal displacement of the cylinder were tested to capture the effect of cylinder eccentricity on the investigating flow pattern and average 𝑁𝑢.
Research Limitations: A detailed investigates is needed in the context of 3D flow. This will be a part of our future work.
Practical Implementations: The effect of a rotating cylinder on heat transfer and fluid flow in a differentially heated rectangular enclosure filled with Power Law non-Newtonian fluid has practical importance in the process industry.
Original/Value: The results of this study may be of some interest to the researchers of the field of chemical or process engineering.
Purpose: The purpose of this paper is to conduct a detailed investigation of the 2D natural convection flow of a dusty fluid. Therefore, the incompressible boundary layer flow of a two-phase particulate suspension is investigated numerically over a semi-infinite vertical flat plate. Comprehensive flow formations of the gas and particle phases are given in the boundary layer region. Primitive variable formulation is employed to convert the nondimensional governing equations into the non conserved form. Three important two-phase mechanisms are discussed, namely, water-metal mixture, oil-metal mixture and air-metal mixture.
Design/Methodology/Approach: The full coupled nonlinear system of equations is solved using implicit two point finite difference method along the whole length of the plate.
Findings: We have presented numerical solution of the dusty boundary layer problem. Solutions obtained are depicted through the characteristic quantities, such as, wall shear stress coefficient, wall heat transfer coefficient, velocity distribution and temperature
distribution for both phases. Results are interpreted for wide range of Prandtl number Pr (0.005-1000.0). It is observed that thin boundary layer structures can be formed when mass concentration parameter or Prandtl number (e.g. oil-metal particle mixture) are high.
Research Limitations: A detailed investigates is needed in the context of 3D flow. This will be a part of our future work.
Practical Implementations: Dusty fluid natural convection is a subject of practical interest in quite a number of industrial applications. These applications are as diverse as, for instance, natural winds, lunar surface erosion by the exhaust of a landing vehicle and dust entrainment in a cloud formed during a nuclear explosion.
Originality/Value: The results of the study may be of some interest to the researchers of the field of chemical engineers.
weighted residual method of finite element analysis has been used for numerical solution. The code validation and grid independency test have been carried out to justify the numerical accuracy. It has been observed that increment of magnetic field reduces the heat transfer rate, whereas
increment of heater distance augments the heat transfer rate significantly. Results are discussed on the basis of Nusselt number (Nu), Bejan number (Be) and shown by contours and 3D plots. It has also been found that = 0.4 always shows better heat transfer rate and entropy optimization.
Design/Methodology/Approach: Finite volume based CFD software, Fluent (Ansys
15.0) is used to solve the governing equations. Attribution of the various flow parameters of fluid flow and heat transfer are investigated including Rayleigh number (Ra) ranging from 10^4 to 10^6, Prandtl number (Pr) from 10 to 1000, Power law index (n) from 0.6 to 1.4, the cylinder radius (R) from 0 to 0.3, and the angular rotational speed (Ω) from -500 to 500. Grid sensitivity analysis is performed and numerically obtained results have been compared with those results available in the literature and found to be in good agreement.
Findings: Outcomes are reported in terms of isotherms, streamlines and average Nusselt number (𝑁𝑢) of the heated wall for various Ra, Pr, n, R and Ω. Vertical and horizontal displacement of the cylinder were tested to capture the effect of cylinder eccentricity on the investigating flow pattern and average 𝑁𝑢.
Research Limitations: A detailed investigates is needed in the context of 3D flow. This will be a part of our future work.
Practical Implementations: The effect of a rotating cylinder on heat transfer and fluid flow in a differentially heated rectangular enclosure filled with Power Law non-Newtonian fluid has practical importance in the process industry.
Original/Value: The results of this study may be of some interest to the researchers of the field of chemical or process engineering.
Purpose: The purpose of this paper is to conduct a detailed investigation of the 2D natural convection flow of a dusty fluid. Therefore, the incompressible boundary layer flow of a two-phase particulate suspension is investigated numerically over a semi-infinite vertical flat plate. Comprehensive flow formations of the gas and particle phases are given in the boundary layer region. Primitive variable formulation is employed to convert the nondimensional governing equations into the non conserved form. Three important two-phase mechanisms are discussed, namely, water-metal mixture, oil-metal mixture and air-metal mixture.
Design/Methodology/Approach: The full coupled nonlinear system of equations is solved using implicit two point finite difference method along the whole length of the plate.
Findings: We have presented numerical solution of the dusty boundary layer problem. Solutions obtained are depicted through the characteristic quantities, such as, wall shear stress coefficient, wall heat transfer coefficient, velocity distribution and temperature
distribution for both phases. Results are interpreted for wide range of Prandtl number Pr (0.005-1000.0). It is observed that thin boundary layer structures can be formed when mass concentration parameter or Prandtl number (e.g. oil-metal particle mixture) are high.
Research Limitations: A detailed investigates is needed in the context of 3D flow. This will be a part of our future work.
Practical Implementations: Dusty fluid natural convection is a subject of practical interest in quite a number of industrial applications. These applications are as diverse as, for instance, natural winds, lunar surface erosion by the exhaust of a landing vehicle and dust entrainment in a cloud formed during a nuclear explosion.
Originality/Value: The results of the study may be of some interest to the researchers of the field of chemical engineers.
reduce the heat transfer area. The inclination of the channel (both positive and negative) induces the generated vortices to get closer to each other and make an enlarged vortex.
Moreover, heat transfer as a form of local and overall average Nusselt number through the coupled thermal boundary layers and the inclined walls is also examined. The details results will be discussed in the full paper.
influenced by the variation of the aforementioned parameters.
periodic temperature. The numerical scheme is based on the finite element method adapted to rectangular non-uniform mesh elements by a non-linear parametric solution algorithm. The fluid considered in this study is air. The results are obtained for the Rayleigh number and Reynolds number ranging from 102 to 104
and 1 to 100, respectively, with constant physical properties for the fluid medium considered. Velocity and temperature profiles, streamlines, isotherms, and average Nusselt numbers are presented to observe the effect of the investigating parameters on fluid flow and heat transfer characteristics. The present results
show that the convective phenomena are greatly influenced by the variation of Rayleigh numbers and Reynolds number.
colder and the remaining walls are maintained as adiabatic. Governing equations of natural convection are solved through the finite volume approach, in which buoyancy is modeled via the
Boussinesq approximation. Effects of different parameters such as Rayleigh number, aspect ratio, prantdl number and heater location are considered. Results show that heat transfer increases when
the heater is moved toward the right corner of the enclosure. It is also revealed that increasing the Rayleigh number, increases the strength of free convection regime and consequently increases the
value of heat transfer rate. Moreover, larger aspect ratio enclosure has larger Nusselt number value. In order to have better insight, streamline and isotherms are shown.
characteristics. The computational model is developed in Ansys Fluent environment based on some simplified assumptions. Three test conditions are selected from the existing literature to verify the numerical model directly, and reasonably good agreement between the model and the test results confirms the reliability of the simulation. Solar radiation flux profile around the tube is also
approximated from the literature. An in house macro is written to read the input solar flux as a heat flux wall boundary condition for the tube wall. The numerical results show that there is an abrupt
variation in the resultant heat flux along the circumference of the receiver. Consequently, the temperature varies throughout the tube surface. The lower half of the horizontal receiver enjoys the
maximum solar flux, and therefore, experiences the maximum temperature rise compared to the upper part with almost leveled temperature. Reasonable attributions and suggestions are made on this particular type of conjugate thermal system. The knowledge that gained so far from this study will be used to further the analysis and to design an efficient concentrator photovoltaic collector in near future.
this process is essential to optimize the drying kinetics and improve energy efficiency of the process. Since material properties varies with moisture content, the models should not consider constant materials properties, constant diffusion .The objective of this paper is to develop a multiphysics based mathematical model to simulate coupled heat and mass transfer during convective drying of fruit considering variable material properties. This model can be used predict the temperature and moisture distribution inside the food during drying. Effect of different drying air temperature and drying air velocity on drying kinetics has been demonstrated. The governing equations of heat
and mass transfer were solved with Comsol Multiphysics 4.3.
in terms of local skin friction and local Nusselt number coefficients."
rectangular cavity is carried out numerically. The flow pattern and heat transfer characteristics are studied for different
values of volume fraction in the range 0 0.2 , Rayleigh number in the range 9 1 Ra 10 and the nano particles with
different thermo physical properties. It was found that for low Rayleigh numbers, heat transfer exhibits a decreasing trend
for increasing values of volume fraction of oxide nanofluids, whereas for higher values of Rayleigh numbers, an increasing
trend of heat transfer was observed due to increase in the volume fraction of nanofluids.
convection of paramagnetic fluids inside a square
cavity has been considered in this study. The cavity is placed
in a microgravity condition (no gravitation acceleration) and
under a uniform magnetic field which acts vertically. A ramp
temperature boundary condition is applied on left vertical side
wall of the cavity where the temperature initially increases
with time up to some specific time and maintain constant
thereafter. A distinct magnetic convection boundary layer is
developed adjacent to the left vertical wall due to the effect
of the magnetic body force generated on the paramagnetic
fluid. An improved scaling analysis has been performed
using triple-layer integral method and verified by numerical
simulations. The Prandtl number has been chosen greater than
unity varied over 5-100. Moreover, the effect of various values
of the magnetic parameter and magnetic Rayleigh number on
the fluid flow and heat transfer has been shown.
adjacent to an inclined semi-infinite plate subject to a
temperature boundary condition which follows a ramp function
up until some specified time and then remains constant is
reported. The development of the flow from start-up to a steadystate
has been described based on scaling analyses and verified
by numerical simulations. Attention in this study has been given
to fluids having a Prandtl number Pr less than unity. The
boundary layer flow depends on the comparison of the time at
which the ramp heating is completed and the time at which the
boundary layer completes its growth. If the ramp time is long
compared with the steady state time, the layer reaches a quasi
steady mode in which the growth of the layer is governed solely
by the thermal balance between convection and conduction. On
the other hand, if the ramp is completed before the layer becomes
steady; the subsequent growth is governed by the balance
between buoyancy and inertia, as for the case of instantaneous
heating.
abruptly heated inclined flat plate is investigated through a
scaling analysis and verified by numerical simulations. In
general, the development of the thermal flow can be
characterized by three distinct stages, i.e. a start-up stage, a
transitional stage and a steady state stage. Major scales including
the flow velocity, flow development time, and the thermal and
viscous boundary layer thicknesses are established to quantify the
flow development at different stages and over a wide range of
flow parameters. Details of the scaling analysis and the numerical
procedures are described in this paper.
The scale formation mechanism in Bayer process equipment is complex and is not yet fully understood. Numerous researchers indicate that scale growth is strongly affected by fluid velocity while also influenced by a number of other factors such as the quality of bauxite ore, rheological properties of fluid, turbulence and inertia of suspended particles and adhesive property of particles. It is common knowledge that, if the particles approach the wall at right angles, the chance to cross the laminar sub layer to accumulate scale on the solid surface increases. The components (stream-wise ( ) and cross-stream ( )) of the fluctuating velocity play a critical role on whether the potential for scale formation is increased or suppressed.
In this chapter, a numerical study using the Finite Volume Method to analyse the fluid dynamics behaviour of water as it flows through a concentric reducer used in the Bayer plant is presented. The simulation results show a significant variation of the stream-wise ( ) and cross-stream ( ) components of the fluctuating velocity as flow passes through the concentric reducer. In the reducer, the cross-stream ( ) component is greater than that at the walls of the straight pipes connected to the reducer. The variation of the cross-stream component of the fluctuating velocity is believed to be accountable for the increase in scale deposition at the reducer section.