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Wyświetlanie 1-15 z 37
Tytuł:
Global stability for thermal convection in a couple-stress fluid with temperature and pressure dependent viscosity
Autorzy:
Choudhary, S. S.
Bharti, P. K.
Powiązania:
https://bibliotekanauki.pl/articles/178230.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
konwekcja
konwekcja cieplna
stabilność
płyn nieniutonowski
convection
thermal convection
stability
non-Newtonian fluid
Opis:
We show that the global nonlinear stability threshold for convection in a couple-stress fluid with temperature and pressure dependent viscosity is exactly the same as the linear instability boundary. This optimal result is important because it shows that linearized instability theory has captured completely the physics of the onset of convection. It has also been found that the couplestress fluid is more stable than the ordinary viscous fluid and then the effect of couple-stress parameter (F) and variable dependent viscosity (Γ) on the onset of convection is also analyzed.
Źródło:
Studia Geotechnica et Mechanica; 2013, 35, 3; 85-102
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Triple- diffusive convection in a micropolar ferrofluid in the presence of rotation
Autorzy:
Chand, S.
Powiązania:
https://bibliotekanauki.pl/articles/265647.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
konwekcja
konwekcja cieplna
substancja rozpuszczalna
pole magnetyczne
namagnesowanie
triple- diffusive convection
micropolar ferrofluid
thermal convection
solute gradient
vertical magnetic field
rotation
magnetization
Opis:
This paper deals with the theoretical investigation of the triple-diffusive convection in a micropolar ferrofluid layer heated and soluted below subjected to a transverse uniform magnetic field in the presence of uniform vertical rotation. For a flat fluid layer contained between two free boundaries, an exact solution is obtained. A linear stability analysis theory and normal mode analysis method have been employed to study the onset convection. The influence of various parameters like rotation, solute gradients, and micropolar parameters (i.e., the coupling parameter, spin diffusion parameter and micropolar heat conduction parameter) on the onset of stationary convection has been analyzed. The critical magnetic thermal Rayleigh number for the onset of instability is also determined numerically for sufficiently large value of the buoyancy magnetization parameter M1 (ratio of the magnetic to gravitational forces). The principle of exchange of stabilities is found to hold true for the micropolar fluid heated from below in the absence of micropolar viscous effect, microinertia, solute gradient and rotation. The oscillatory modes are introduced due to the presence of the micropolar viscous effect, microinertia , solute gradient and rotation, which were non-existent in their absence. In this paper, an attempt is also made to obtain the sufficient conditions for the non-existence of overstability.
Źródło:
International Journal of Applied Mechanics and Engineering; 2013, 18, 2; 307-327
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Electro-hydrodynamic convection in a rotating dielectric micropolar fluid layer
Autorzy:
Kaur, H.
Verma, G. N.
Powiązania:
https://bibliotekanauki.pl/articles/264654.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
konwekcja
liczba Rayleigha
liczba Taylora
convection
rotation
electric
Rayleigh number
Taylor number
normal mode
Opis:
Thermal convection of a rotating dielectric micropolar fluid layer under the action of an electric field and temperature gradient has been investigated. The dispersion relation has been derived using normal mode analysis. The effects of the electric Rayleigh number, micropolar viscosity, Taylor number and Prandtl number on stability and over stability criteria are discussed. It is found that rotation postpones the instability in the fluid layer, while the Prandtl number and rotation both have a stabilizing effect. It is also observed that the micropolar fluid additives have a stabilizing effect, whereas the electric field has a destabilizing effect on the onset of convection stability.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 4; 106-124
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chaotic convection of viscoelastic fluid in porous medium under G-jitter
Autorzy:
Bhadauria, B. S.
Singh, A.
Singh, M. K.
Powiązania:
https://bibliotekanauki.pl/articles/265559.pdf
Data publikacji:
2019
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
teoria nieliniowa
grawitacja
konwekcja
non-linear theory
gravity modulation
chaotic convection
Opis:
The present article aims at investigating the effect of gravity modulation on chaotic convection of a viscoelastic fluid in porous media. For this, the problem is reduced into Lorenz system (non-autonomous) by employing the truncated Galerkin expansion method. The system shows transitions from periodic to chaotic behavior on increasing the scaled Rayleigh number R. The amplitude of modulation advances the chaotic nature in the system while the frequency of modulation has a tendency to delay the chaotic behavior which is in good agreement with the results due to [1]. The behavior of the scaled relaxation and retardation parameter on the system is also studied. The phase portrait and time domain diagrams of the Lorenz system for suitable parameter values have been used to analyze the system.
Źródło:
International Journal of Applied Mechanics and Engineering; 2019, 24, 1; 37-51
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Marangoni convection in a relatively hotter or cooler liquid layer with free boundaries
Autorzy:
Gupta, A. K.
Shandil, R. G.
Powiązania:
https://bibliotekanauki.pl/articles/265233.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
napięcie powierzchniowe
konwekcja
przewodzenie
stabilność liniowa
surface tension
convection
conducting
linear stability
Opis:
In this paper, we study the onset of cellular convection in a horizontal fluid layer heated from below, with a free-slip boundary condition at the bottom when the driving mechanism is surface tension at the upper free surface, in the light of the modified analysis of Banerjee et al. (Jour. Math. & Phys. Sci., 1983, 17, 603). This leads to a formulation of the problem which depends upon whether the liquid layer is relatively hotter or cooler. It is found that the phenomenon of surface tension driven instability problems should not only depend upon the Marangoni number which is proportional to the maintained temperature differences across the layer but also upon another parameter that arises due to variation in the specific heat at constant volume on account of the variations in temperature. Numerical results are obtained for the problem wherein the lower free boundary is perfectly thermally conducting.
Źródło:
International Journal of Applied Mechanics and Engineering; 2013, 18, 2; 581-588
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Wyznaczanie gęstości strumienia ciepła konwekcji wymuszonej w przepływie laminarnym w przewodach prostoosiowych metodą elementów brzegowych
Determination of heat flux density of forced convection flows through straight pipes by the Boundary Element Method
Autorzy:
Teleszewski, T. J.
Powiązania:
https://bibliotekanauki.pl/articles/404095.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Symulacji Komputerowej
Tematy:
metoda elementów brzegowych
laminarny przepływ jednokierunkowy
strumień ciepła
konwekcja
konwekcja wymuszona
boundary element method
laminar unidirectional flow
heat flux
convection
forced convection
Opis:
W pracy przedstawiono algorytm MEB do analizy pól temperatury i gęstości strumienia ciepła przy przepływie laminamym z wymianą ciepła w przewodach prostoosiowych o dowolnym kształcie przekroju poprzecznego. Zaprezentowano sformułowanie zagadnienia przy użyciu metody elementów brzegowych do opisu przepływu i wymiany ciepła w przepływie jednokierunkowym przez przewód o dowolnym kształcie przekroju poprzecznego. Przedstawiono graficzne rezultaty obliczeń przepływu z udziałem konwekcji wymuszonej w profilowanym przewodzie prostoosiowym.
The paper presents the numerical application Boundary Element Method to analyze the temperature and heat flux density distribution of forced convection laminar flows through straight pipes with arbitrary cross-section shapes. Integral formulations the problems of the fluid flow and heat exchange for the case of the laminar unidirectional flow with heat transfer was presented. Moreover graphical results of the numerical calculations the velocity, temperature and heat flux of laminar flow in the profiled straight pipe were presented.
Źródło:
Symulacja w Badaniach i Rozwoju; 2014, 5, 2; 143-153
2081-6154
Pojawia się w:
Symulacja w Badaniach i Rozwoju
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Combined effects of helical force and rotation on stationary convection of a binary ferrofluid in a porous medium
Autorzy:
Kpossa, M.
Monwanou, A. V.
Powiązania:
https://bibliotekanauki.pl/articles/2174187.pdf
Data publikacji:
2022
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
konwekcja
ferrofluid
ośrodek porowaty
helical force
stationary convection
binary mixture of ferrofluid
porous medium
rotation
Opis:
This work studies the simultaneous effects of helical force, rotation and porosity on the appearance of stationary convection in a binary mixture of a ferrofluid and on the size of convection cells. We have determined the analytical expression of the Rayleigh number of the system as a function of the dimensionless parameters. The effect of each parameter on the system is studied. The consideration of the simultaneous effect of the basic characteristics made it possible to determine the evolution of the convection threshold in the ferrofluid and then the size of convection cells. The analyzes of the various results obtained allowed us to deduce whether the convection sets in quickly or with a delay when the various effects taken into account in the study are considered simultaneously.
Źródło:
International Journal of Applied Mechanics and Engineering; 2022, 27, 2; 158--176
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The complex Ginzburg Landau model for an oscillatory convection in a rotating fluid layer
Autorzy:
Manjula, S. H.
Kiran, P.
Reddy, P. Raj
Bhadauria, B. S.
Powiązania:
https://bibliotekanauki.pl/articles/266148.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
konwekcja
teoria nieliniowa
liczba Nusselta
convection
finite amplitude
nonlinear theory
rotation modulation
Nusselt number
Opis:
A weakly nonlinear thermal instability is investigated under rotation speed modulation. Using the perturbation analysis, a nonlinear physical model is simplified to determine the convective amplitude for oscillatory mode. A non-autonomous complex Ginzburg-Landau equation for the finite amplitude of convection is derived based on a small perturbed parameter. The effect of rotation is found either to stabilize or destabilize the system. The Nusselt number is obtained numerically to present the results of heat transfer. It is found that modulation has a significant effect on heat transport for lower values of ωf while no effect for higher values. It is also found that modulation can be used alternately to control the heat transfer in the system. Further, oscillatory mode enhances heat transfer rather than stationary mode.
Źródło:
International Journal of Applied Mechanics and Engineering; 2020, 25, 1; 75-91
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of magnetic field dependent viscosity on ferromagnetic convection in a rotating sparsely distributed porous medium - revisited
Autorzy:
Prakash, J.
Kumar, P.
Manan, S.
Sharma, K. R.
Powiązania:
https://bibliotekanauki.pl/articles/265547.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
ferrofluid
konwekcja
pole magnetyczne
materiał porowaty
convection
rotation
magnetic field dependent viscosity
porous medium
Opis:
The effect of magnetic field dependent (MFD) viscosity on the thermal convection in a ferrofluid layer saturating a sparsely distributed porous medium has been investigated by using the Darcy-Brinkman model in the simultaneous presence of a uniform vertical magnetic field and a uniform vertical rotation. A correction is applied to the study of Vaidyanathan et al. [11] which is very important in order to predict the correct behavior of MFD viscosity. A linear stability analysis has been carried out for stationary modes and oscillatory modes separately. The critical wave number and critical Rayleigh number for the onset of instability, for the case of free boundaries, are determined numerically for sufficiently large values of the magnetic parameterM1 . Numerical results are obtained and are illustrated graphically. It is shown that magnetic field dependent viscosity has a destabilizing effect on the system for the case of stationary mode and a stabilizing effect for the case of oscillatory mode, whereas magnetization has a destabilizing effect.
Źródło:
International Journal of Applied Mechanics and Engineering; 2020, 25, 1; 142-158
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of thermal modulation on double diffusive convection in the presence of applied magnetic field and internal heat source
Autorzy:
Manjula, S. H.
Suresh, P.
Rao, M. G.
Powiązania:
https://bibliotekanauki.pl/articles/1839901.pdf
Data publikacji:
2021
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
analiza nieliniowa
płyn newtonowski
konwekcja
thermal modulation
weak nonlinear analysis
internal heating
newtonian fluid
double diffusive convection
Opis:
The investigation of thermal modulation on double-diffusive stationary convection in the presence of an applied magnetic field and internal heating is carried out. A weakly nonlinear stability analysis has been performed using the finite-amplitude Ginzburg-Landau model. This finite amplitude of convection is obtained at the third order of the system. The study considers three different forms of temperature modulations. OPM-out of phase modulation, LBMO-lower boundary modulation, IPM-in phase modulation. The finite-amplitude is a function of amplitude ,Tδ frequency ω and the phase differenceθ . The effects of Tδ and ω on heat/mass transports have been analyzed and depicted graphically. The study shows that heat/mass transports can be controlled effectively by thermal modulation. Further, it is found that the internal Rayleigh number iR enhances heat transfer and reduces the mass transfer in the system.
Źródło:
International Journal of Applied Mechanics and Engineering; 2021, 26, 1; 135-155
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Triple-diffusive convection in Walters' (Model B') fluid with varying gravity field saturating a porous medium
Autorzy:
Kango, S. K.
Rana, G. C.
Chand, R.
Powiązania:
https://bibliotekanauki.pl/articles/178886.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
lepkosprężyste ciecze Walters B
ciecz Waltersa
ośrodek porowaty
konwekcja
Walters' (model B') fluid
Walters' B liquid model
Walters' B' fluid
porous media
convection
Opis:
The Triple-Diffusive convection in Walters’ (Model B') fluid with varying gravity field is considered in the presence of uniform vertical magnetic field in porous medium. For the case of stationary convection, the magnetic field, varying gravity field and the stable solute gradients have stabilizing effects whereas the medium permeability has destabilizing (or stabilizing) effect on the system under certain conditions. A linear stability analysis theory and normal mode analysis method have been carried out to study the onset convection. The kinematic viscoelasticity has no effect on the stationary convection. The solute gradients, magnetic field, varying gravity field, porosity and kinematic viscoelasticity introduce oscillatory modes in the system, which were non-existent in their absence. The sufficient conditions for the non-existence of overstability are also obtained. The results are also shown graphically.
Źródło:
Studia Geotechnica et Mechanica; 2013, 35, 3; 45-56
0137-6365
2083-831X
Pojawia się w:
Studia Geotechnica et Mechanica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Similarity solution for combined free-forced convection past a vertical porous plate in a porous medium with a convective surface boundary condition
Autorzy:
Garg, P.
Purohit, G. N.
Chaudhary, R. C.
Powiązania:
https://bibliotekanauki.pl/articles/265568.pdf
Data publikacji:
2016
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
płyta porowata
tarcie
ośrodek porowaty
konwekcja
combined convection
fixed vertical porous plate
skin-friction coefficient
Nusselt number
convective surface boundary condition
porous medium
Opis:
This paper studies the mathematical implications of the two dimensional viscous steady laminar combined free-forced convective flow of an incompressible fluid over a semi infinite fixed vertical porous plate embedded in a porous medium. It is assumed that the left surface of the plate is heated by convection from a hot fluid which is at a temperature higher than the temperature of the fluid on the right surface of the vertical plate. To achieve numerical consistency for the problem under consideration, the governing non linear partial differential equations are first transformed into a system of ordinary differential equations using a similarity variable and then solved numerically under conditions admitting similarity solutions. The effects of the physical parameters of both the incompressible fluid and the vertical plate on the dimensionless velocity and temperature profiles are studied and analysed and the results are depicted both graphically and in a tabular form. Finally, algebraic expressions and the numerical values are obtained for the local skin-friction coefficient and the local Nusselt number.
Źródło:
International Journal of Applied Mechanics and Engineering; 2016, 21, 4; 827-836
1734-4492
2353-9003
Pojawia się w:
International Journal of Applied Mechanics and Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Pomiary parametrów cieplnych przekładni zębatych
Measurements of heat parameters in cylindrical gears
Autorzy:
Tomaszewski, J.
Rysiński, J.
Powiązania:
https://bibliotekanauki.pl/articles/157994.pdf
Data publikacji:
2007
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
temperatura
ciepło
tarcie
konwekcja
heat balance
temperature
friction
convection
Opis:
Temperatura jako jeden z podstawowych parametrów diagnostycznych ma bardzo duży wpływ na charakter pracy przekładni. Dlatego w pracy przedstawiono doświadczalne metody pomiaru parametrów cieplnych przekład-ni. Badania przeprowadzono na stanowisku mocy zamkniętej.
Temperature is one of the basic parameters used for an assessment of gear work conditions. In a real object, the registration of temperature in some characteristic points is needed. Therefore, in the paper the experimental investigation of heat parameters in characteristic points are presented. The experimental investigations were performed on the power-closed-loop test stand (called also back-to-back rig or circulating power test stand).
Źródło:
Pomiary Automatyka Kontrola; 2007, R. 53, nr 12, 12; 35-37
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects of rotation on Jeffrey nanofluid flow saturated by a porous medium
Autorzy:
Rana, Gian C.
Powiązania:
https://bibliotekanauki.pl/articles/1839839.pdf
Data publikacji:
2021
Wydawca:
Politechnika Częstochowska. Wydawnictwo Politechniki Częstochowskiej
Tematy:
nanofluid
Jeffrey model
convection
porous medium
rotation
nanopłyn
model Jeffreya
konwekcja
medium porowate
rotacja
Opis:
In this paper, the effects of rotation on a Jeffery nanofluid flow in a porous medium which is heated from below is studied. Darcy model is employed for porous medium and the Jeffrey fluid model is used as a base fluid. The Navier-Stokes equations of motion of fluid are modified under the influence of the Jeffrey parameter, naoparticles and rotation. The basic perturbation technique based on normal modes is applied to derive the dispersion relation for a Rayleigh number. The effects of the Taylor number, Jeffrey parameter, Lewis number, modified diffusivity ratio, nanoparticles Rayleigh number and medium porosity on the stationary convection of the physical system have been analyzed analytically and graphically. It is observed that the rotation parameter has a stabilising influence for both bottom/top-heavy configurations.
Źródło:
Journal of Applied Mathematics and Computational Mechanics; 2021, 20, 3; 17-29
2299-9965
Pojawia się w:
Journal of Applied Mathematics and Computational Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The effect of regulating elements on convective heat transfer along shaped heat exchange surfaces
Autorzy:
Cernecky, J.
Koniar, J.
Brodnianska, Z.
Powiązania:
https://bibliotekanauki.pl/articles/185818.pdf
Data publikacji:
2013
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
heat transfer
convection
holographic interferometry
przenikanie ciepła
konwekcja
interferometria holograficzna
Opis:
The paper deals with a study of the effect of regulating elements on local values of heat transfer coefficients along shaped heat exchange surfaces with forced air convection. The use of combined methods of heat transfer intensification, i.e. a combination of regulating elements with appropriately shaped heat exchange areas seems to be highly effective. The study focused on the analysis of local values of heat transfer coefficients in indicated cuts, in distances expressed as a ratio x/s for 0; 0.33; 0.66 and 1. As can be seen from our findings, in given conditions the regulating elements can increase the values of local heat transfer coefficients along shaped heat exchange surfaces. An optical method of holographic interferometry was used for the experimental research into temperature fields in the vicinity of heat exchange surfaces. The obtained values correspond very well with those of local heat transfer coefficients [alfa]x, recorded in a CFD simulation.
Źródło:
Chemical and Process Engineering; 2013, 34, 1; 5-16
0208-6425
2300-1925
Pojawia się w:
Chemical and Process Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 37

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