Abstract
The effect of vertical throughflow on the onset of convection in a horizontal layer of a porous medium saturated by a nanofluid is studied analytically. The model used for the nanofluid incorporates the effects of Brownian motion and thermophoresis. The dependences of the critical Rayleigh number for the non-oscillatory and oscillatory modes of instability on the thermophoresis and Brownian motion parameters for the cases with and without throughflow are investigated.
Similar content being viewed by others
Abbreviations
- c :
-
Nanofluid specific heat at constant pressure
- c p :
-
Specific heat of the nanoparticle material
- D B :
-
Brownian diffusion coefficient
- D T :
-
Thermophoretic diffusion coefficient
- F :
-
Parameter defined by Eq. 52
- g :
-
Gravitational acceleration
- H :
-
Dimensional layer depth
- J T :
-
Parameter defined by Eq. 46
- \({J_{\phi}}\) :
-
Parameter defined by Eq. 48
- k :
-
Thermal conductivity of the nanofluid
- k m :
-
Effective thermal conductivity of the porous medium
- k p :
-
Thermal conductivity of the nanoparticle material
- K :
-
Permeability of the porous medium
- K T :
-
Parameter defined by Eq. 47
- \({K_{\phi}}\) :
-
Parameter defined by Eq. 49
- Le :
-
Lewis number, defined by Eq. 16
- N A :
-
Modified diffusivity ratio, defined by Eq. 20
- N B :
-
Modified particle-density increment, defined by Eq. 21
- N 1 :
-
Parameter defined by Eq. 50
- N 2 :
-
Parameter defined by Eq. 51
- p*:
-
Pressure
- p :
-
Dimensionless pressure, p*K/μα m
- Q :
-
Péclet number defined by Eq. 15
- Ra :
-
Thermal Rayleigh–Darcy number, defined by Eq. 17
- Rm:
-
Basic-density Rayleigh number, defined by Eq. 18
- Rn:
-
Concentration Rayleigh number, defined by Eq. 19
- t*:
-
Time
- t :
-
Dimensionless time, t*α m/σ H 2
- T*:
-
Nanofluid temperature
- T :
-
Dimensionless temperature, \({\frac{T^{\ast}-T^{\ast}_{\rm c}}{T^\ast_{\rm h} -T^\ast_{\rm c}}}\)
- \({T^{\ast}_{\rm c}}\) :
-
Temperature at the upper wall
- \({T^{\ast}_{\rm h}}\) :
-
Temperature at the lower wall
- (u, v, w):
-
Dimensionless Darcy velocity components, (u*, v*, w*)H/α m
- v :
-
Dimensionless Darcy velocity
- v*:
-
Dimensional Darcy velocity, (u*, v*, w*)
- V*:
-
Vertical throughflow velocity
- (x, y, z):
-
Dimensionless Cartesian coordinates, (x*, y*, z*)/H; z is the vertically upward coordinate
- (x*, y*, z*):
-
Cartesian coordinates
- α :
-
Dimensionless horizontal wavenumber
- α m :
-
Thermal diffusivity of the porous medium, \({\frac{k_{\rm m}}{(\rho c_{\rm p} )_{\rm f}}}\)
- ε :
-
Porosity of the porous medium
- λ:
-
Parameter defined by Eq. 27
- μ :
-
Viscosity of the fluid
- ρ :
-
Fluid density
- ρ p :
-
Nanoparticle mass density
- (ρc)f :
-
Heat capacity of the fluid
- (ρc)m :
-
Effective heat capacity of the porous medium
- σ :
-
Parameter defined by Eq. 8
- \({\phi^{\ast}}\) :
-
Nanoparticle volume fraction
- \({\phi_{0}^{\ast}}\) :
-
Nanoparticle volume fraction at the lower wall
- \({\phi_{1}^{\ast}}\) :
-
Nanoparticle volume fraction at the upper wall
- \({\phi}\) :
-
Relative nanoparticle volume fraction, \({\frac{\phi^{\ast}-\phi^{\ast}_0}{\phi^{\ast}_1 -\phi^{\ast}_0}}\)
- ω :
-
Dimensionless frequency
- *:
-
Dimensional variable
- ′:
-
Perturbation variable
- b:
-
Basic solution
References
Buongiorno J.: Convective transport in nanofluids. ASME J. Heat Transfer 128, 240–250 (2006)
Buongiorno, J., Hu, W.: Nanofluid coolants for advanced nuclear power plants, Paper no. 5705. Proceedings of ICAPP ’05 Seoul, 15–19 (2005)
Buongiorno J., Hu L., Kim S.J., Hannink R., Truong B., Forrest E.: Nanofluids for enhanced economics and safety of nuclear reactors: An evaluation of the potential features, issues, and research gaps. Nucl. Technol. 162, 80–91 (2008)
Choi, S.: Enhancing thermal conductivity of fluids with nanoparticle. In: Siginer, D.A., Wang, H.P. (eds.) Developments and Applications of Non-Newtonian Flows, ASME FED-vol. 231/ MD-vol. 66, pp. 99–105 (1995)
Choi S.U.S.: Nanofluids: from vision to reality through research. ASME J. Heat Transfer 131, 033106 (2009)
Choi S.U.S., Zhang Z.G., Yu W., Lockwood F.E., Grulke E.A.: Anomalous thermal conductivity enhancement in nanotube suspensions. Appl. Phys. Lett. 79, 2252–2254 (2001)
Choi S.U.S., Zhang Z., Keblinski P.: Nanofluids. In: Nalwa, H. (ed.) Encyclopedia of Nanoscience and Nanotechnology, pp. 757–773. American Scientific Publishers, New York (2004)
Das S., Choi S.U.S., Yu W., Pradeep T.: Nanofluids Science and Technology. Wiley, Hoboken (2008)
Eastman J.A., Choi S.U.S., Li S., Yu W., Thompson L.J.: Anomalously increased effective thermal conductivities of ethylene glycol-based nanofluids containing copper nanoparticles. Appl. Phys. Lett. 78, 718–720 (2001)
Kim S.J., McKrell T., Buongiorno J., Hu L.: Enhancement of flow boiling critical heat flux (CHF) in alumina/water nanofluids. Adv. Sci. Lett. 2, 100–102 (2009)
Kleinstreuer C., Li J., Koo J.: Microfluidics of nano-drug delivery. Int. J. Heat Mass Transf. 51, 5590–5597 (2008)
Kuznetsov A.V., Nield D.A.: Thermal instability in a porous medium layer saturated by a nanofluid: Brinkman model. Transp. Porous Media 81, 409–422 (2010)
Lee S., Choi S.U.S., Li S., Eastman J.A.: Measuring thermal conductivity of fluids containing oxide nanoparticles. ASME J. Heat Transfer 121, 280–289 (1999)
Masuda H., Ebata A., Teramae K., Hishinuma N.: Alteration of thermal conductivity and viscosity of liquid by dispersing ultra-fine particles. Netsu Bussei 7, 227–233 (1993)
Nield D.A.: Convective instability in porous media with throughflow. AIChE J. 33, 1222–1224 (1987)
Nield D.A., Bejan A.: Convection in Porous Media, 3rd ed. Springer, New York (2006)
Nield D.A., Kuznetsov A.V.: Thermal instability in a porous medium layer saturated by a nanofluid. Int. J. Heat Mass Transf. 52, 5796–5801 (2009)
Nield D.A., Kuznetsov A.V.: The effect of local thermal nonequilibrium on the onset of convection in a nanofluid. ASME J. Heat Transfer 132, 052405 (2010)
Rea U., McKrell T., Hu L., Buongiorno J.: Laminar convective heat transfer and viscous pressure loss of alumina–water and zirconia–water nanofluids. Int. J. Heat Mass Transf. 52, 2042–2048 (2009)
Wu C., Cho T.J., Xu J., Lee D., Yang B., Zachariah M.R.: Effect of nanoparticle clustering on the effective thermal conductivity of concentrated silica colloids. Phys. Rev. E 81, 011406 (2010)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Nield, D.A., Kuznetsov, A.V. The Effect of Vertical Throughflow on Thermal Instability in a Porous Medium Layer Saturated by a Nanofluid. Transp Porous Med 87, 765–775 (2011). https://doi.org/10.1007/s11242-011-9717-x
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11242-011-9717-x