M.Z.I. Bangalee’s research while affiliated with University of Dhaka and other places

An airfoil is the shape of a wing. Simply put, it is the cross-section of any lift and drag-producing body. For an airplane to take flight, the most important part is played by the wings. The interaction between air and the wings of an aircraft can be tricky as there are several parameters at work. As stated above, an airfoil is a cross-section of a wing and, therefore, two-dimensional. Analyzing a two-dimensional body is both time and resource-efficient. The objective of this thesis is to study the impact and determine the factors that govern the flow around a modified airfoil in turbulence. In extreme situations, such as a tropical storm, the wing of an airfoil might get damaged and result in an accident. This work will further demonstrate the traits of the airfoil in such a situation. The forces acting on an airfoil like lift, drag, and the changes in momentum will all be discussed in the present study.

Radiofrequency ablation is a nominally invasive technique to eradicate cancerous or non-cancerous cells by heating. However, it is still hampered to acquire a successful cell destruction process due to inappropriate RF intensities that will not entirely obliterate tumorous tissues, causing in treatment failure. In this study, we are acquainted with a nanoassisted RF ablation procedure of cardiac tumor to provide better outcomes for long-term survival rate without any recurrences. A three-dimensional thermo-electric energy model is employed to investigate nanothermal field and ablation efficiency into the left atrium tumor. The cell death model is adopted to quantify the degree of tissue injury while injecting the Fe3O4 nanoparticles concentrations up to 20% into the target tissue. The results reveal that when nanothermal field extents as a function of tissue depth (10 mm) from the electrode tip, the increasing thermal rates were approximately 0.54362%, 3.17039%, and 7.27397% for the particle concentration levels of 7%, 10%, and 15% compared with no-particle case. In the 7% Fe3O4 nanoparticles, 100% fractional damage index is achieved after ablation time of 18 s whereas tissue annihilation approach proceeds longer to complete for no-particle case. The outcomes indicate that injecting nanoparticles may lessen ablation time in surgeries and prevent damage to adjacent healthy tissue.

Cryosurgery is demarcated as cell annihilation by freezing temperature yielded through a cryogenic probe. Thermal distributions nearby the adjacent blood vessels can impede the iceball evolution and surgery success. Hence it is indispensable to predict the dynamic temperature and iceball propagations in biological tissues and its implications earlier through simulation methods. In this study, a transient two-phase flow and heat transfer model is presented to envisage the thermal extents inside and outside cryoprobes. The bioheat transfer model is adopted to inspect the temperature evolutions during multiprobe cryosurgery of hepatic tissues embedded without or with blood vessels. During computer simulation, a 3D geometry model is introduced as the living tissue vicinities embedded with two simplified hepatic arteries when multiple cryogenic probes are injected into the tissues with uniform insertion depth system. The tissues are pondered as non-ideal materials in which phase transition occurs over a temperature range, and the effects of blood perfusion and metabolic heat generation in the tissues are also considered. Computational analyses are then carried out to scrutiny the impact of the blood vessels on the temperature developments of tissues. The results show that when blood vessels are treated as a heat source during treatment, oscillatory thermal outlines are found along the anticipated pathways during multiprobe cryosurgery, and the relative maximum temperature increased upto ∼98 % at the midpoint of the route BB′ for the ablation time of 100 s. The irregular ice fronts are also obtained with the manifestation of blood vessels compared with no blood vessel case, and the iceball volume enclosed by the − 40°C isothermal front decreased significantly from 22.94 cm3 (without blood vessels) to 6.92 cm3 (with blood vessels) for the ablation time of 300 s. The simulation outcomes indicate that multiprobe cryosurgery is more effective to destroy the tumor tissue properly when the target tissue is located faraway from blood vessels. The simulation platform is anticipated to be valuable in optimizing pre-treatment plans of cryosurgery schemes while determining the number and position of cryoprobes in the neighborhood of blood vessels.

Atherosclerotic with the high occurrence of plaque formation due to stenosis has attracted wide attention among researchers. The left coronary artery has been studied in two-dimensional and in three-dimensional (3D) bifurcation as the models of blood flow through Newtonian and non-Newtonian fluids to better understand the physical mechanism. The computational Fluid Dynamics (CFD) technique is incorporated in COMSOL Multiphysics and then it is justified by satisfactory validation. It is found that the Newtonian model shows larger recirculation zones than non-Newtonian does. The present study also focuses on the evaluations of the lesion of diagnostic and the coefficient of pressure drop assessments on the basis of the diagnostic parameter’s critical values affected by the rheological model. Nevertheless, the leading concentration of the subsisting investigation works is confined to the change of importance factor (IFc) affected by arterial blockage. But the IFc of non-Newtonian fluid for 3D left coronary artery bifurcation model decreases with increasing bifurcation angle and the time-averaged inlet pressure is the least for smaller bifurcation angles. The current research further concentrates that the flow separation length reduces with developing bifurcation angle in bifurcated geometry. It is significant to mention that non-Newtonian blood flow model incorporating hemodynamic and diagnostic parameters has great impacts on instantaneous flow systems.

A body which tends to block the flow is a bluff body. Flow investigation over a cube shaped bluff body is a matter of interest in building aerodynamics and vehicle aerodynamics for its general shape. Several CFD methods used earlier to read the complex flow behavior around a cube. In this article, flow behavior over a cube shaped bluff body is computed numerically at Reynold’s number 40000. Four turbulence models have been used to capture the complex flow behavior around the cube and some aerodynamic properties like the drag force co-efficient and effects of angle of attack is also investigated. The three-dimensional viscous air flow is assumed as steady, incompressible and turbulent. A structured hexahedral mesh topology is generated to mesh the three-dimensional cube including the surrounding domain. A grid independent finite volume upwind scheme is used to solve the flow equations. The results are compared with previous experimental data and with a recent work. The drag force coefficient, C d of the cube is compared with the conventional C d of a cube. The results give a good agreement with the available experimental result for RNG k-ε and k-ω SST turbulence model. The variation of the velocity profile, pressure coefficient and the change of drag force co-efficient are computed in a basis of the angle of attack at 0° ≤ α ≤ 15° and discussed in details. This research can help to find the flow behavior like separation and reattachment of a cube including aerodynamic characteristics like airflow distribution and drag reduction.

Objective of this study is to analysis the MHD flow over a curved stretching surface. In this model we incorporated the radiation, mixed convection and partial slip parameter. Using a curvilinear coordinate system developed a mathematical model and the system of basic governing equations are converted into ordinary differential equations with appropriate transformations. The obtained results are solved by using bvp4c solver. The numerical; results for the velocity and temperature as well as the physical quantities such as skin friction and rate of heat transfer are determined and discussed through graph. Results shown that the velocity and temperature decreases with increasing values of curvature parameter and but for magnetic parameter velocity decreases whereas temperature profile increase. Comparison with previous literature are also shown in tabular form and found excellent agreement. Dhaka Univ. J. Sci. 69(3): 171-178, 2022 (June)

A modified multiphase flow model is applied for a better understanding of bio-nanofluid (blood containing 4% (w/v) Fe3O4 nanoparticles) flow regimes through a real bifurcated artery. The magnetic field with distinct current intensities (I = 0 – 300 A) was employed to induce the flow features when the wire's source is placed nearby the junction of the asymmetrical branched artery during numerical computation. The finite volume method was used to solve the coupled hemodynamics model. Results show that the pressure, and vorticity profiles increased and fallen gradually with the existence of the magnetic source and further obtained the maximum pressure for the strong current intensity (I = 300 A). The fluctuating vorticity distributions are found along the inner and outer vessel wall as well as the predicted lines created within the simulated domain for the increase of current intensity. The velocity outlines variates steadily, and the local peak velocities are obtained with the increase of the magnetic force. With the increment of the current intensity upto I = 300 A, the flow rate rises progressively for the asymmetric branched vessel, and the opposite scenario is found for the root vessel. The temperature profiles decrease steadily with the increment of the applied current intensity. With the manifestation of the magnetic source, the irregular flow behaviours are found within the asymmetrical bifurcated artery. This modeling investigation could be beneficial for the emergent therapy plan of ample vascular diseases as the magnetic drug targeting system.