Below is a curated list of publications that represent my research journey. Each work reflects a dedication to advancing the frontiers of technical knowledge and showcases the collaborative spirit of scientific achievement. These publications not only underscore my commitment to innovation and rigorous inquiry but also serve as a testament to the impact of thorough research and thoughtful analysis.
1. Computational simulation for the prediction of rocket turbine’s blade flutter
Khairuzzaman Mamun
Abstract: This study is to predict the flutter of the first rotor blade of the two-stage axial turbine of a rocket engine turbopump, where the turbine was designed by the Japan Aerospace Exploration Agency (JAXA) in the project of Dynamic Design Team (DDT). The number of blade counts of the first rotor of the turbine is 36. A pre-stressed modal analysis has been carried out using ANSYS Mechanical 18.1 on a single rotor blade using fixed support at the hub and rotational velocity boundary conditions, for getting natural frequencies and mode shapes (eigenvectors). The first four modes of Inconel 718 and Titanium 64 blade have been taken for the CFD calculation. However, ANSYS CFX 18.1 has been taken as the solver for the CFD calculation of the simulations. Reynolds Average Navier Stoke’s equations have been used as the governing equation. H2 ideal gas has been considered as a working fluid. Shear Stress Transport (SST) model has been used as the turbulence model. At the inlet, total pressure and total temperatures are 7.55 MPa and 500 K respectively. At the outlet, static pressure is 1.71 MPa. The blade wall has been considered as a no-slip, whereas the slip wall has been considered for the hub and casing. The rotational speed of the rotor blade has taken as 60600 rpm where the rotational axis is Z-axis. A transient blade row model has been used for the unsteady calculations. Results of this study have been presented by graphical and contour representations. Aerodynamic damping coefficient and blade’s wall work per cycle have been taken as the parameters for the analysis. However, the stability of Inconel and Titanium blades is predicted for -90 ≤ IBPA ≤ +90 degrees, whereas instability or flutter of the blades may occur when -180 ≤ IBPA < -90 degrees or +90 < IBPA ≤ +180 degrees.
Khairuzzaman Mamun and Ken-ichi Funazaki
Abstract: Arterial elasticity has become a vital predictor of cardiovascular diseases in the past few years, so numerical simulations have been done for a comparative study of blood flow through an elastic stenotic artery with a rigid stenotic artery. The wall of the vessels is considered to be rigid as well as elastic. Young’s modulus and Poisson’s ratio of the elastic wall of the artery are 1.08 MPa and 0.49 respectively. The blood has been considered as non-Newtonian fluid for the simulations. Physiological and parabolic velocity profile has been imposed for inlet boundary condition. Reynolds number at the inlet has been ranged approximately from 86 to 966 for the investigation. The laminar model has been used as a governing equation. The simulations have been performed by using ANSYS Fluent 18.1. The deformation of the arteries has been modelled as a two-way fluid-structure interaction (FSI) using the ANSYS package. Comparative results from the arteries of the rigid and elastic wall have been presented by graphical representations. Blood velocity, pressure, and wall shear stress have been taken as the numerical parameters. Thus, differences between rigid and deformed walls have been checked based on Blood velocity, pressure, and wall shear stress for different time steps.
Khairuzzaman Mamun, Ken-ichi Funazaki, Sharmin Akter and Most. Nasrin Akhter
Abstract: The effect of magnetic field on blood flow is a very significant topic for bio-medical engineers as the ferrofluids are widely used nowadays in the industry and medicines. The ferrofluids are used as magnetic separation tool, anti-cancer drug carrier, micro-valve application, etc. One important application of these fluids is in chemotherapy application. Besides, the magnetic field can control the heat and blood flow characteristics through the arteries. It has an effect on the resistance to blood flow through arteries. Thus, in this paper, the effect of magnetic field on blood flow through arteries has been discussed. The most recent findings from various research articles are described herein in a systematic way. Moreover, some important results from the articles are presented here. It is observed that the blood flow resistance in a vessel is mainly regulated by the vessel’s radius and length of the blood vessel. Moreover, as the magnetic strength and size of the magnetic particles increase, the accumulation of nano-particles increases, as well. It is also found that the effect of doubling the magnetic field from 4 to 8 tesla increases the pressure drop by nearly 15%, but it shows marginal influence on the wall shear stress.
Khairuzzaman Mamun, Ken-ichi Funazaki and Most. Nasrin Akhter
Abstract: Numerical simulations have been done for a statistical analysis to investigate the effect of stenotic shapes and spiral flows on wall shear stress in the three-dimensional idealized stenotic arteries. Non-Newtonian flow has been taken for the simulations. The wall of the vessel is considered to be rigid. Physiological, parabolic and spiral velocity profile has been imposed for inlet boundary condition. Moreover, the time-dependent pressure profile has been taken for outlet boundary condition. Reynolds number at the inlet has been ranged approximately from 86 to 966 for the investigation. Low Reynolds number k-w model has been used as governing equation. 120 simulations have been performed for getting the numerical results. However, the numerical results of wall shear stress have been taken for the statistical analysis. The simulations and the statistical analysis have been performed by using ANSYS-18.1 and SPSS respectively. The statistical analyses are significant as p-value in all cases are zero. The eccentricity is the most influencing factor for WSSmax. The WSSmin has been influenced only by the flow spirality. The stenotic length has an influence only on the WSSmax whereas the stenotic severity has an influence on the WSSmax and WSSave.
5. Comparative study of Newtonian and Non-Newtonian blood flow through a stenosed carotid artery
Mohammad Matiur Rahman, Md. Anwar Hossain, Khairuzzaman Mamun and Most. Nasrin Akhter
A numerical simulation to investigate the Non-Newtonian modeling effects on physiological flows in a three dimensional idealized stenosed carotid artery with 75% severity (by area) is taken from patient specific model. The wall vessel is considered to be rigid. Oscillatory physiological and parabolic velocity profile has been imposed for inlet boundary condition. Where the physiological waveform was performed using a Fourier series with sixteen harmonics. The investigation has a Reynolds number range of 94 to 1120. Low Reynolds number k − ω model is used as governing equation. The investigation has been carried out to characterize two Non-Newtonian constitutive equations of blood, namely, (i) Carreau and (ii) Cross models. The Newtonian model has been investigated also to study the physics of fluid. The results of Newtonian model are compared with the Non-Newtonian models. The numerical results are presented in terms of pressure, wall shear stress distributions and the streamlines contours. At early systole pressure differences between Newtonian and Non-Newtonian models are observed at pre-stenotic, throat and immediately after throat regions. In the case of wall shear stress, some differences between Newtonian and Non-Newtonian models are observed when the flows are the minimum such as at early systole or diastole. It is known that blood is Bingham plastic fluid. So the viscosity of blood will decrease with increase in shear rate and when shear rate will be greater than 100 then viscosity will be constant. The viscosity of Newtonian model is less than that of non-Newtonian model when shear rate is less than 100, but viscosity of all models is equal when shear rate is equal to 100. When Reynolds number is very low then pressure and WSS of Newtonian model will be less than that of non-Newtonian model but opposite scenario will be seen for velocity distribution. Since early systole and diastole there are comparatively low Reynolds numbers, the results of Newtonian and non-Newtonian condition may be different at early systole and diastole. On the other hand maximum Reynolds number is seen at peak systole. So the results of Newtonian and non Newtonian condition follow each other at peak systole. Again the velocity of the throat region is high for any time instant. So the results of Newtonian and non Newtonian condition may be same at the throat region but different at the pre and post stenotic region. The results of pressure, WSS, and velocity distribution are discussed below with respective figure.
6. Comparative study of Newtonian physiological blood flow through normal and stenosed carotid artery
Mohammad Matiur Rahman, Md. Anwar Hossain, Khairuzzaman Mamun, and Most. Nasrin Akhter
A numerical simulation is performed to investigate Newtonian physiological flows behavior on three dimensional idealized carotid artery (CA) and single stenosed (75% by area) carotid artery(SCA). The wall vessel is set as rigid during simulation. Bifurcated blood vessel are simulated by using three-dimensional flow analysis. Physiological and parabolic velocity profiles are set out to fix the conditions of inlet boundaries of artery. In other hand, physiological waveform is an important part of compilation and it is successfully done by utilization of Fourier series having sixteen harmonics. The investigation has a Reynolds number range of 94 to 1120. Low Reynolds numberk — ω model has been used as governing equation. The investigation has been carried out to characterize the flow behavior of blood in two geometry, namely, (i) Normal carotid artery (CA) and (ii) Stenosed carotid artery (SCA). The Newtonian model has been used to study the physics of fluid. The findings of the two models are thoroughly compared in order to observe there behavioral sequence of flows. The numerical results were presented in terms of velocity, pressure, wall shear stress distributions and cross sectional velocities as well as the streamlines contour. Stenosis disturbs the normal pattern of blood flow through the artery as reduced area. At stenosis region velocity and peak Reynolds number rapidly increase and Reynolds number reach transitional and turbulent region. These flow fluctuation and turbulence have bad effect to the blood vessel which makes to accelerate the progress of stenosis.
7. Attributes of oscillatory physiological blood flow through 3-D geometry of single stenosed artery
Khairuzzaman Mamun, Mohammad Ali and Most. Nasrin Akhter
Abstract: The present study investigates the significant changes of flow behavior for 65 and 85 percentages severities of stenosis by area. The blood is assumed to be incompressible, homogeneous and Newtonian, while artery is assumed to be a rigid wall. The transient analysis is performed using ANSYS-14.5. Oscillatory physiological and parabolic velocity profile has been imposed for inlet boundary condition. The investigation has a Reynolds number range of 96 to 800. Pressure based solver and finite volume method are used for calculations. The flow pattern, wall shear stress (WSS), pressure, velocity, streamline contours, cross sectional and Centre-line velocity distribution are observed at early-systole, peak-systole and diastole for better understanding of arterial disease. Wall Shear Stress distribution shows that as severity increases, shearing of flow also increases for all cases. Thus maximum stress is exerted in throat region at peak systole. Pressure distribution also demonstrates that at all cases 85% stenotic artery creates more force than 65% stenotic artery at their pre-stenotic region. Interestingly, a recirculation region is visible at the post stenotic region in 85% stenotic artery for all cases and recirculation region increases with increasing minimum velocity at the inlet flow. From streamline contours it can be interpreted that 85% stenosis can create vortex at any time phase. So 85% stenosis is very harmful for its high probability of creating vortex.
8. Physiological non-Newtonian blood flow through several doubly stenosed arteries
Most. Nasrin Akhter, Khairuzzaman Mamun, M.M. Rahman, and M. Ali
Abstract: A numerical analysis of physiological blood flow in a three-dimensional artery with double stenosis has been performed to observe the flow behavior. The vessel wall is considered to be rigid. The degree of stenosis has been varied for the analysis. 65%-65%, 65%-85%, 85%-65% and 85%-85% by area reduction are examined for four doubly stenosed arteries. Physiological and parabolic velocity profiles have been imposed for inlet boundary conditions. The investigation covers a Reynolds number range of 96 to 800. A low Reynolds number k -ω model is used in the governing equations. Non-Newtonian constitutive equations of Cross models are used for the simulation. The numerical results are presented in terms of velocity, pressure, wall shear stress (WSS) distributions and cross-sectional velocities as well as the streamlines contours. The maximum wall shear stress is noted in the throat region at peak systole. Throats of 85% reduction of cross sectional area create more change in wall shear stress than the throat of 65% cross-sectional area at any time-phase in all geometries. Pressure distributions demonstrate that in every case, the pressure difference in a 85%-85% stenotic artery is higher than that in the other three stenotic arteries. Velocity increases in the throat regions as a function of the increases in severity of the stenosis. Turbulence is observed downstream of the throats of 85% stenosis in all geometries. The flows in throats of 85% reduction of cross-sectional area in all geometries create a recirculation region downstream of the throat region and the recirculation region increases with an increase of the minimum velocity of inlet flow.
9. Physiological non-Newtonian blood flow through single stenosed artery
Khairuzzaman Mamun, Mohammad Matiur Rahman, Most. Nasrin Akhter, and Mohammad Ali
Abstract: A numerical simulation to investigate the Non-Newtonian modelling effects on physiological flows in a three dimensional idealized artery with a single stenosis of 85% severity. The wall vessel is considered to be rigid. Oscillatory physiological and parabolic velocity profile has been imposed for inlet boundary condition. Where the physiological waveform is performed using a Fourier series with sixteen harmonics. The investigation has a Reynolds number range of 96 to 800. Low Reynolds number k – ω model is used as governing equation. The investigation has been carried out to characterize two Non-Newtonian constitutive equations of blood, namely, (i) Carreau and (ii) Cross models. The Newtonian model has also been investigated to study the physics of fluid. The results of Newtonian model are compared with the Non-Newtonian models. The numerical results are presented in terms of pressure, wall shear stress distributions and the streamlines contours. At early systole pressure differences between Newtonian and Non-Newtonian models are observed at pre-stenotic, throat and immediately after throat regions. In the case of wall shear stress, some differences between Newtonian and Non-Newtonian models are observed when the flows are minimum such as at early systole or diastole.
10. Characteristics of Pulsatile Blood Flow Through 3-D Geometry of Arterial Stenosis
Khairuzzaman Mamun, Most. Nasrin Akhter, Md. Shirazul Hoque Mollah, Md. Abu Naim Sheikh, Mohammad Ali
Abstract: A numerical simulation is carried out to demonstrate the significant changes of flow behaviour for two different severities of arterial stenosis. Two stenosis levels of 65% and 85% are considered by area. The blood is considered as flowing fluid and assumed to be incompressible, homogeneous and Newtonian, while artery is assumed to be a rigid wall. The transient analysis is performed using ANSYS-14.5. The flow pattern, wall shear stress (WSS), pressure contours, and Centre-line velocity distribution are observed at early-systole, peak-systole and diastole for better understanding of arterial disease. Wall Share Stress distribution shows that as severity increases, sharing of flow also increases for all cases. Thus maximum stress is exerted in throat region at peak systole. The pressure distribution demonstrates that at all cases 85% stenotic artery creates more force than 65% stenotic artery at their pre-stenotic region. Interestingly, a recirculation region is visible at the post stenotic region in 85% stenotic artery for all cases and recirculation region increases with the decrease of the inlet flow velocity. Analysis indicates that the significant flow changes happen in the post stenotic region.
Essay:
An Overview of Phase Change, Isotherm, and Isotherm Migration Method
Khairuzzaman Mamun 