Wyniki wyszukiwania - BazTech

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Numerical study of MHD Williamson-nano fluid flow past a vertical cone in the presence of suction/injection and convective boundary conditions

Sathyanarayana Manthri, Goud Tamtam Ramakrishna

Archives of Thermodynamics

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2023

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Vol. 44, no 2

115--138

EN

The primary objective is to perform a numerical synthesis of a Williamson fluid that has nanoparticles added to it and is directed toward a vertical cone in a uniform transverse magnetic field, under heat and mass transport, suction and injection, and convective boundary conditions. For this particular fluid flow, by utilising similarity transformations, the partial differential equations are transformed into ordinary differential equations. Calculating these kinds of equations with their suitable bounds requires the Runge–Kutta technique in combining a shooting strategy. The functions of a vast number of parameters are graphically represented and assessed on flow field profiles. The results show the local skin friction, local Nusselt number, and local Sherwood number and the changing values of the flow constraints. Finally, the results are compared to those from the previously published works and found to be in good agreement.

2

Strouhal number effects on dynamic boundary layer evolution over a wedge surface from initial flow to steady flow: analytical approach

Bachiri Mohamed, Bouabdallah Ahcen

International Journal of Applied Mechanics and Engineering

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2022

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Vol. 27, no. 4

26--39

EN

The present work studies the effects of the physical parameter characterizing the laminar flow regime, namely the Strouhal number, on the evolution of the unsteady dynamic boundary-layer developed along a wedge surface. Similarity method is used to transform unsteady momentum equation to dimensionless form. Using superposition method between diffusion and convective flows solutions, an ad hoc velocity profile formula is proposed. The obtained results confirm perfectly the numerical data given by Blasius, Falkner-Skan and Williams-Rhyne for all Strouhal numbers. A new accurate analytical function of the local skin friction is established for all time values and for different wedge surface directions. In order to give further clarification on the flows evolutions from diffusion flow to convective flow, in the whole space domain, new skin friction coefficient curves are plotted for all Strouhal numbers and for different wedge surface directions.

3

Convective and non-convective wind gusts in Poland, 2001-2015

Kolendowicz L., Taszarek M., Czernecki B.

Meteorology Hydrology and Water Management. Research and Operational Applications

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2016

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Vol. 4, iss. 2

15--21

EN

The main aim of the article is to present the climatology of the peak wind gust frequency in Poland caused by the impact of both atmospheric circulation and the presence of thunderstorm clouds. Nine meteorological stations for the measurement period of 2001-2015 were taken into account. Only SYNOP reports with a peak wind gust higher or equal to 15 m s-1 in thunderstorm and non-thunderstorm days are considered in this study. The results indicate that the highest threat in terms of frequency and strength of peak wind gusts due to convection occurs in July. In winter, thunderstorms are rare, but if they occur, about 80% of them produce wind gusts exceeding a threshold of 15 m s-1. Peak wind gusts in a non-thunderstorm days are the highest and the most frequent in January, and are at a minimum during summer. Comparing both types, peak wind gusts during days with a thunderstorm were on average stronger than those without an involved convection. This indicated that convection was an important factor in enhancing the strength of a wind gust. The highest value in our base was 34 m s-1, recorded in Kraków on 8th July 2015 within the occurrence of a severe thunderstorm, while the highest value in a day without a thunderstorm was 33 m s-1, recorded in Łódź on 31st January 2002.

4

Span-wise fluctuating MHD convective flow of a viscoelastic fluid through a porous medium in a hot vertical channel with thermal radiation

Singh K. D.

International Journal of Applied Mechanics and Engineering

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2016

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Vol. 21, no. 3

667--681

EN

An unsteady mixed convection flow of a visco-elastic, incompressible and electrically conducting fluid in a hot vertical channel is analyzed. The vertical channel is filled with a porous medium. The temperature of one of the channel plates is considered to be fluctuating span-wise cosinusoidally, i.e., [...]. A magnetic field of uniform strength is applied perpendicular to the planes of the plates. The magnetic Reynolds number is assumed very small so that the induced magnetic field is neglected. It is also assumed that the conducting fluid is gray, absorbing/emitting radiation and non-scattering. Governing equations are solved exactly for the velocity and the temperature fields. The effects of various flow parameters on the velocity, temperature and the skin friction and the Nusselt number in terms of their amplitudes and phase angles are discussed with the help of figures.

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Konstrukcje rękawic z aluminiowanych tkanin bazaltowych zapewniających ochronę przed czynnikami termicznymi. Część II: Badania użytkowe w warunkach przemysłowych

Hrynyk R., Frydrych I.

Przegląd Włókienniczy - Włókno, Odzież, Skóra

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2015

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nr 9

34--36

EN

There are presented the results of utility trials done on the new models of gloves protecting against the thermal and mechanical factors. Gloves were produced with the use of aluminized basalt fabrics. The construction and composition were designed in the Central InstituteforLabour Protection - National Research Institute [1]. On the basis of prepared questionaries’ the positive assessment of elaborated models of gloves, which underwent the utility trials in the real conditions on the labour stands. It is confirmation of good selection of material packages and construction during the stage of designing the protective gloves with the use of aluminized basalt fabrics.

6

Konstrukcje rękawic z aluminiowanych tkanin bazaltowych zapewniających ochronę przed czynnikami termicznymi. Część I: Badania laboratoryjne parametrów ochrony

Hrynyk R., Frydrych I.

Przegląd Włókienniczy - Włókno, Odzież, Skóra

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2015

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nr 6

28--33

EN

There were presented in the aspect of construction and material composition existing on the market models of gloves protecting against the thermal factors, and six new glove models produced on the basis of aluminized basalt fabrics, designed in the Central Institute for Labour Protection - National Research Institute. The obtained results of resistance on the mechanical factors (abrasion, tear resistance, puncture and cut resistance as well as thermal factors (resistance on the contact, convective, and radiation heat, flammability, and resistance on the small metal splashes) in each variant confirmed the fulfillment of requirements of appropriate standards.

7

Oscillatory MHD convective flow of second order fluid through porous medium in a vertical rotating channel in slip-flow regime with heat radiation

Garg B. P., Singh K. D., Bansal A. K.

International Journal of Applied Mechanics and Engineering

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2015

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Vol. 20, no. 1

33--52

EN

An analysis of an oscillatory magnetohydrodynamic (MHD) convective flow of a second order (viscoelastic), incompressible, and electrically conducting fluid through a porous medium bounded by two infinite vertical parallel porous plates is presented. The two porous plates with slip-flow condition and the no-slip condition are subjected respectively to a constant injection and suction velocity. The pressure gradient in the channel varies periodically with time. A magnetic field of uniform strength is applied in the direction perpendicular to the planes of the plates. The induced magnetic field is neglected due to the assumption of a small magnetic Reynolds number. The temperature of the plate with no-slip condition is non-uniform and oscillates periodically with time and the temperature difference of the two plates is assumed high enough to induce heat radiation. The entire system rotates in unison about the axis perpendicular to the planes of the plates. Adopting complex variable notations, a closed form solution of the problem is obtained. The analytical results are evaluated numerically and then presented graphically to discuss in detail the effects of different parameters of the problem. The velocity, temperature and the skin-friction in terms of its amplitude and phase angle have been shown graphically to observe the effects of the viscoelastic parameter γ, rotation parameter Ω, suction parameter […], Grashof number Gr, Hartmann number M, the pressure A, Prandtl number Pr, radiation parameter N and the frequency of oscillation […].

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Transient unsteady natural convection MHD flow past a semi-infinite verticaI plate with constant heat flux

Palani G., Ganesan P.

International Journal of Applied Mechanics and Engineering

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2007

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Vol. 12, no 1

125-134

EN

A numerical analysis is performed to study the MHD flow of an electrically conducting, incompressible, viscous fluid past a semi-infinite vertical plate with constant heat flux, subjected to a transversely applied magnetic field. The heat due to viscous dissipation and the induced magnetic field are assumed to be negligible. The dimensionless goveming equations are unsteady, two-dimensional, coupled, and non-linear. A most accurate, unconditionally stable and fast converging implicit finite difference scheme is used to solve the non-dimensional goveming equations. Velocity and temperature of the flow have been presented graphically for various parameters. The local and average skin friction and Nusselt number are also presented graphically.