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1
Content available remote Vibrational effect on heat transfer and entropy generation in a circular porous cavity
100%
Mahmud S. , Fraser R. A.
International Journal of Applied Mechanics and Engineering
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2004
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tom Vol. 9, no 3
523-533
EN
We investigate the nature of heat transfer and entropy generation for natural convection in a two-dimensional circular section enclosure vibrating sinusoidally perpendicular to the applied temperature gradient in a zero-gravity field. The enclosure is assumed to fill with porous media. The Darcy momentum equation is used to model the porous media. The full governing differential equations are simplified with the Boussinesq approximation and solved by a finite volume method. Whereas the Prandtl number Pr is fixed to 1.0. Results are presented in terms of the average Nusselt number (Nuav), entropy generation number (Nsav), Bejan number (Beav), and kinetic energy (KEav).
2
Content available remote Free convection inside a vertical inphase wavy cavity
100%
Mahmud S. , Fraser R. A.
International Journal of Applied Mechanics and Engineering
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2004
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tom Vol. 9, no 3
535-545
EN
We examined the heat transfer and fluid flow characteristics inside a bent cavity made of two horizontal straight walls and two vertical bent walls. Bent walls are assumed to follow a profile of cosine curve. Horizontal straight walls are kept adiabatic, while the bent walls are isothermal but kept at different temperatures. Laminar nature convection inside the cavity is considered. Governing equations were discretized using the Finite Volume method with collocated variable arrangement. Simulation was carried out for a range of wave ratio 'lambda' = 0.00-0.6, aspect ratio A = 1.0-4.0, and Rayleigh number Ra = 100-107 for a fluid having Prandtl number 1.0. Streamlines and isothermal lines are used to present the corresponding flow and thermal field inside the enclosure. Local and global distributions of Nusselt number are presented for the above configuration. Lastly, velocity profiles are presented for some selected cases of A and 'lambda' inside the enclosure for better understanding of the influence of flow field on the thermal field.
3
Content available Characterization of semolina protein film with incorporated zinc oxide nano rod intended for food packaging
80%
Jafarzadeh S. , Alias A. , Ariffin F. , Mahmud S.
Polish Journal of Food and Nutrition Sciences
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2017
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tom 67
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nr 3
EN
This study intended to provide biopolymer films used as food packaging, which will result in reducing environmental pollution produced by the activities of synthetic food packaging. We used zinc oxide nanorods (ZnO-nr) and we prepared nanocomposite films by means of solvent casting. FTIR and SEM were employed to characterize the final films. SEM images revealed that ZnO-nr particles were homogenously distributed throughout the film surface. The thermal, optical, and heat sealability properties of the films were also examined. Adding ZnO-nr signifi cantly reduced oxygen permeability and heat sealability. The semolina films’ UV absorbance was highly impacted by the degree of ZnO-nr addition. The nanocomposite films absorbed above 90% of the near infrared spectra. In addition, the zeta potential revealed the surface charge of ZnO-nr had a negative charge of about -33.9 mV
4
Content available remote Separation characteristics of fluid flow in a pipe with wavy surface
80%
Mahmud S. , Mamun M. A. H. , Sadrul Islam A. K. M.
International Journal of Applied Mechanics and Engineering
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2002
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tom Vol. 7, no 4
1263-1278
EN
Separation characteristics of fluid flow in a pipe with sinusoidal wavy surface are investigated numerically. The pipe waviness is characterized by a wavelength ('lambda') and an amplitude (a) of the wave. Steady laminar flow of a Newtonian fluid is considered. Governing equations are discretized using the control volume based Finite-Volume method with collocated variable arrangement. SIMPLE algorithm is used and TDMA solver is applied to solve the system of equations. The length of the pipe is kept four times the wavelength (4*'lambda'). The effect of surface waviness, determined by the wavelength-amplitude ratio 'lambda'/a (=L*) , on separation characteristics of fluid flow is presented. The simulation work has been carried out for L*= 11.0 - 30.0 and for the Reynolds number ranging from 50 to 2000. The structure of separation bubble depends strongly on the waviness of the surface for a particular Reynolds number and changes a little with the wave number n. Finally the flow field is presented in the form of stream function and axial velocity profiles for understanding the separation phenomenon.
5
Investigation on the workability and compressive strength of concrete by using bagasse ash from sugar mill
70%
Mahmud S. , Islam M. I. , Ali R. B. , Islam M. M. , Hasan M. M.
World Scientific News
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2018
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tom 96
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