Browsing by Author "Khalilur Rahman, Md."

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    Acoustics of rectangular flat plates with free-simply supported and clamped-simply supported edge conditions
    (Department of Mechanical Engineering, 1989-08) Khalilur Rahman, Md.; Wahhaj Uddin, Dr. Md.
    For abstract please see full text
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    Experimental study of wear characteristics during cutting ' V ' - threads
    (Department of Industrial and Production Engineering, BUET, 1988-09) Khalilur Rahman, Md.; Khan, Dr. Ahsan Ali
    There are several factors like relative motion and positionof the tool and work piece, diameter of the work. piece, diameter of the work piece and depth of cut whicl"have a great influence on the tool wear, particularly, quring thread cutting process~ The present study has taken an , attempt to investigate the cl"aracteristics of tool wear duting cutting V-threads. Anumber of threads have been cut with selected- pitch, diameter and depth of threads in order to show the relationships of tool Wear"ith pitch and diameter of threads. wear readings were recorded under microscope for each case. Someimportant characteristics of. tool wear have been found out from this study. All findings have been justified.by some established principles of metal cuttingbased on several past research works. The study shows an important characteristic.' that wears on right cutting edge are al'iays greater than that on left cutting edge for a right cut tool .• Investigations show that cl"ange of static tool geometry during actual cutting process can be considered as responsib.1e for th'is characteristic. ,Ho,;ever, this nature of unequal wani' may lead the tool for regrinding very soon,because Wear on rig:tlt cutting edge reaches its critical value before the Wf'tone. iii In order to avoid this difficu1ty, a mathematical model has been deve10ped to specifY the static tool geometry \
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    Numerical study of unsteady laminar multiphase flow through a rectangular curved duct .
    (Department of Mathematics, BUET, 2024-01-20) Khalilur Rahman, Md.; Md. Abdul Hakim Khan, Dr.
    Multiphase flows in curved ducts are used in many industrial processes, such as water treatment, oil production, water desalination, refrigeration, air conditioning, and other food systems and material handling processes. Fluid flow in curved ducts differs from straight ducts due to centrifugal force from curvature, which induces secondary vortices and rapid fluid motion. These phenomena, pivotal for heat transfer enhancement, can lead to fluid instability and mixing. This thesis critically assesses current research on secondary flow in rectangular and curved ducts, identifying gaps in understanding and evaluating published numerical and experimental studies. This study introduces a novel design methodology and mesh system to develop a groundbreaking three-dimensional numerical model for multiphase fluid flow in curved ducts, addressing prior constraints. The model utilizes a finite element method employing the Galerkin approach of weighted residuals to solve the governing Navier-Stokes and Level-set equations, effectively capturing the physical phenomena with appropriate boundary conditions. The current study focuses on numerically examining the characteristics of unsteady laminar multiphase flow within a rectangular curved duct. Subsequently, the investigation extends to incorporate the presence of a porous medium and the influence of an external magnetic force. Additionally, heat transfer analysis is conducted to evaluate its impact within the duct. The study investigates the influence of particle concentration, aspect ratio, curvature, Hartmann number, and Dean number on velocity contour, vector plot of flow field, axial velocity and temperature distribution. Additionally, it provides a comparison of two-phase flow among different fluids. The results indicate that as curvature, Dean number, and high-viscosity flow increase, the instability characteristics of the flow decrease. Furthermore, the study presents average velocity magnitudes pertinent to viscosity, porosity, particle concentration, curvature, and Dean number.