# مقالههای Hamid Niazmand

**توجه:**محتویات این صفحه به صورت خودکار پردازش شده و مقالههای نویسندگانی با تشابه اسمی، همگی در بخش یکسان نمایش داده میشوند.

##### ۱Effects of slip and Marangoni convection on single fuel droplet heat–up in the presence of thermal radiation

اطلاعات انتشار:
ششمین کنگره بین المللی مهندسی شیمی،
سال ۱۳۸۸

تعداد صفحات:
۷

Slip and Marangoni convection effects on an isolated fuel droplet heat up process are numerically studied in the presence of thermal radiation. For small droplets, when the droplet size becomes comparable to the mean free paths of the surrounding gas molecules, the continuum hypothesis breaks down and it is important to account for the gas rarefaction effects including velocity slip and temperature jump at the gas–liquid interface. Gas phase velocity slip at the liquid interface reduces the momentum transfer to the liquid phase, while temperature jump at the interface acts as a thermal contact resistance, and therefore, both effects reduce the heat transfer to the fuel drop. In addition, the variationof surface tension along the surface of the fuel droplet, which causes the well–known Marangoni convection, is taken into account in the presence of thermal radiation which can play an important role in the heat up process of fuel drops. It is shown that the presence of thermal radiation in some fuels leads to a more uniform drop surface temperature and therefore, opposing the Marangoni convection effects.<\div>

##### ۲numeriacl study of hemodynamic wall parameters in highly curved arteries with stenosis

اطلاعات انتشار:
هفدهمین کنفرانس سالانه مهندسی مکانیک،
سال ۱۳۸۸

تعداد صفحات:
۶

Geometry of large or medium size arteries known as the predisposed site of atherosclerosis formation has a strong influence on flow pattern and wall shear stress (WSS) dis tribution.<\div>

##### ۳Numerical study of fin spaces on designing parameters of adsorption chillers

اطلاعات انتشار:
نوزدهمین همایش سالانه مهندسی مکانیک،
سال ۱۳۹۰

تعداد صفحات:
۴

In this paper the performance of an adsorption chiller is investigated by solving heat and mass transfer equations for adsorber in a general coordinates system. In order to study the adsorption chiller numerically, the governing equations are solved in four domains of thermal fluid, metal tube, fins and adsorbent bed simultaneously. One of the influential parameters on the adsorption chiller performance is the conductivity of bed, which is commonly low in practical cases. Employing extended surfaces can improve the heat transfer and compensate for the low conductivity of the bed. In the present study the effects of fin spacing on two important parameters of the bed that are specific cooling power(SCP) and coefficient of performance(COP) are examined.<\div>

##### ۴Detailed Investigation of Rarefied Flow inMicro\Nano Lid–driven Cavities Using DSMC

اطلاعات انتشار:
نوزدهمین همایش سالانه مهندسی مکانیک،
سال ۱۳۹۰

تعداد صفحات:
۴

We use DSMC technique to investigate hydrodynamic and thermal characteristic of rarefied hydrogen flow in micro\nano lid–driven cavity. Flow behavior in all rarefaction regimes including slip, transition and free molecular ones has been studied. It is seen that center of primary vortex moves to the left and toward the drivenlid as Kn number increases. Moreover, wall shear stress and heat flux are decreased at higher degrees of rarefaction. It is also observed that wall slip motion is more pronounced in the slip regime and the slop smoothes as Kn grows.<\div>

##### ۵Simulation of Rarefied Gas Flow in Micro\Nano Cavity Using DSMC

اطلاعات انتشار:
دهمین همایش انجمن هوافضای ایران،
سال ۱۳۸۹

تعداد صفحات:
۸

Direct simulation Mont Carlo (DSMC) is a molecular approach which is widely used to model rarefied gas flow in a wide range of Knudsen numbers. Lid–driven cavity is a common geometry used in Micro\Nanoelectro– mechanical systems (MEMS\NEMS). In this paper, DSMC approach is utilized to compare hydrodynamic and thermal characteristic of monatomic and diatomic gasses, namely argon and nitrogen flow in micro\nano lid–driven cavity at transition and free molecular regimes. It is seen that compressibility effect for the monatomic gas is more pronounced. It is also seen that center of vortex is shifted downward to the right of the cavity as the non–equilibrium effects increase. Moreover, the heat transfer to the wall is higher for argon flow in comparison with nitrogen flow.<\div>

##### ۶CFD Analysis of Laminar Natural Convection from a Horizontal Circular Cylinder to its Concentric Elliptic Enclosure

اطلاعات انتشار:
پانزدهمین کنفرانس دینامیک شاره ها (سیالات)،
سال ۱۳۹۲

تعداد صفحات:
۱۲

In the present paper, using a two–dimensional numerical simulation, the heat transfer from a hot circular cylinder to a cold vertical elliptic enclosure has been studied parametrically. The effect of ratio of cylinder radius to the half minor axis length of vertical elliptic enclosure (R ⁄b) on the rate of the heat transfer has been investigated for the Rayleigh number 10(4) and 10(5) . Governing equations have been solved using the finite volume method and TDMA in an ADI procedure. Results show that the patterns of streamlines, isotherms and the Nusselt number values depend strongly on Rayleigh number and ratio of R ⁄b. Furthermore, it is observed that by increasing the Rayleigh number and the ratio of R\b, the heat transfer rate is increased. For instance, when the ⁄ value is changed from 0.2 to 0.6 at Ra=10(5) , the Nusselt number is increased about 55 percent of its initial value. Also when the Raleigh number is risen from 10(4) to 10(5) at R ⁄b , the Nusselt number is climbed almost 65 percent of its initial value.<\div>

##### ۷Positioning angle effects on the melting time of a tall rectangular enclosure; using the Lattice Boltzmann method

اطلاعات انتشار:
کنفرانس بین المللی علوم مهندسی، هنر و حقوق،
سال ۱۳۹۴

تعداد صفحات:
۱۳

The melting process of phase change materials (PCM) in a tall rectangular enclosure with a variable positioning angle has been numerically investigated using a D2Q9 enthalpy based Lattice Boltzmann method. The enclosure with the aspect ratio of 0.5 is heated isothermally on one side, while all other sides are thermally insulated.An immersed moving boundary condition is employed to model the interface between liquid and solid phase. Three positioning angles of0°, 45° and 90°, which produce relatively different melting patterns, are considered. The time variations of the melting line, flow patterns in themelt pool, and temperature distribution are thoroughly examined. The results indicate that changing the positioning angle leads to noticeablevariations in flow and melting patterns, which are more pronounced at higher inclination angles. Moreover, it was found that the total meltingtime decreases almost linearly by increasing the positioning angle, such that there are about 17.5 and 36 percent reductions in total melting timeas the positioning angle increases to 45o and 90o, respectively. Therefore, heat transfer operation of melting PCM systems can be simply controlled by the enclosure orientation.<\div>

##### ۸On study of Electro–osmotic flow in a micro channel with obstacles using the Lattice–Boltzmann method

اطلاعات انتشار:
کنفرانس بین المللی علوم مهندسی، هنر و حقوق،
سال ۱۳۹۴

تعداد صفحات:
۱۴

Motivated by the growing interest in the recent amount of attention received by nano and microchannels, electro–osmotic flows (EOFs) have become a reliable no moving part strategy to control fluid motion in various lab–on–chip devices. In the present work, a relatively new Lattice Boltzmann model has been used to study the electro–osmotic flows in a 2–D flat microchannel.The governing equations are presented in the continuum model, while a set of equivalentequations in Lattice Boltzmann model is introduced and solved numerically. The Nernest–Plank equation is employed to model the internal potential field to obtain more accurate results.Afterwards, different patterns for various numbers of circles have been proposed and thensolved. The studies have been carried out on different sets of one, two and three circle settings to gain a better understanding of the fluid flow and later study its mixing inside the channel. It has been noticed that eccentric placement of the circles and placing them in an oscillating pattern helps the mixing effect.<\div>

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