<abstract xmlns="http://www.w3.org/1999/xhtml"><p>The present study investigates the onset of penetrative convection in- duced by selective absorption of radiation in a magnetic nanofluid saturated porous medium. The influence of Brownian motion, thermophoresis, and magnetophoresis on magnetic nanofluid treatment is taken into consideration. The Darcy’s model is selected for the porous medium. We conduct a linear stability analysis to examine the onset of instability and evaluate the results for two different configurations, namely, when the layer is heated from below and when the layer is heated from above. The numerical investigations are carried out by applying the Chebyshev pseudospectral method. The effect of the porosity parameter <italic>E</italic>, parameter <italic>Y</italic> (represents the ratio of internal heating to boundary heating), Lewis number <italic>Le</italic>, concentration Rayleigh number <italic>Rn</italic>, Langevin parameter <italic>αL</italic>, width of nanofluid layer <italic>d</italic>, diffusivity ratio <italic>η</italic>, and modified diffusivity ratio <italic>NA</italic> is examined at the onset of convection. The results indicate that the convection commences easily with an increase in the value of <italic>Y, Le</italic>, and <italic>NA</italic> but opposite in the case with a decrease in the value of <italic>E</italic>, <italic>αL</italic>, <italic>η</italic> and <italic>d</italic> for both the two configurations. The parameter <italic>Rn</italic> advances the onset of convection when the layer is heated from below, while delays the onset of convection when the layer is heated from above.</p></abstract>

The present study investigates the onset of penetrative convection in- duced by selective absorption of radiation in a magnetic nanofluid saturated porous medium. The influence of Brownian motion, thermophoresis, and magnetophoresis on magnetic nanofluid treatment is taken into consideration. The Darcy’s model is selected for the porous medium. We conduct a linear stability analysis to examine the onset of instability and evaluate the results for two different configurations, namely, when the layer is heated from below and when the layer is heated from above. The numerical investigations are carried out by applying the Chebyshev pseudospectral method. The effect of the porosity parameter E, parameter Y (represents the ratio of internal heating to boundary heating), Lewis number Le, concentration Rayleigh number Rn, Langevin parameter αL, width of nanofluid layer d, diffusivity ratio η, and modified diffusivity ratio NA is examined at the onset of convection. The results indicate that the convection commences easily with an increase in the value of Y, Le, and NA but opposite in the case with a decrease in the value of E, αL, η and d for both the two configurations. The parameter Rn advances the onset of convection when the layer is heated from below, while delays the onset of convection when the layer is heated from above.

Penetrative convection due to absorption of radiation in a magnetic nanofluid saturated porous layer

Studia Geotechnica et Mechanica

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

The present study investigates the onset of penetrative convection in- duced by selective absorption of radiation in a magnetic nanofluid saturated porous...

			I_C-I_C		I_C-I_CHF		I_C-F_CHF

J	Y	η	k_c	Ra_c	k_c	Ra_c	k_c	Ra_c
+1	1	0.001	2.23	0.6144	1.76	0.3656	1.35	0.1476
		0.004	2.18	1.9434	1.74	1.2343	1.32	0.5100
		0.007	2.12	2.7561	1.72	1.8437	1.29	0.7712
		0.010	2.05	3.2883	1.70	2.2875	1.25	0.9622
	5	0.001	2.22	0.1298	1.76	0.0761	1.36	0.0304
		0.004	2.23	0.4957	1.76	0.2934	1.35	0.1176
		0.007	2.22	0.8236	1.76	0.4938	1.35	0.1980
		0.001	2.22	1.1151	1.76	0.6776	1.34	0.2717
	10	0.001	2.22	0.0653	1.76	0.0382	1.36	0.0153
		0.004	2.23	0.2549	1.76	0.1497	1.35	0.0597
		0.007	2.23	0.4337	1.76	0.2561	1.35	0.1019
		0.010	2.23	0.6013	1.76	0.3574	1.35	0.1418
–1	1	0.001	2.18	0.6640	1.75	0.3920	1.35	0.1554
		0.004	2.01	2.4104	1.69	1.5500	1.3	0.6131
		0.007	1.82	3.5526	1.61	2.5300	1.24	1.0167
		0.010	1.63	4.2320	1.53	3.2718	1.17	1.3456
	5	0.001	2.22	0.1322	1.76	0.0773	1.36	0.0308
		0.004	2.20	0.5312	1.75	0.3117	1.35	0.1238
		0.007	2.17	0.9254	1.74	0.5477	1.35	0.2172
		0.010	2.15	1.3071	1.74	0.7831	1.35	0.3106
	10	0.001	2.22	0.0659	1.76	0.0385	1.36	0.0154
		0.004	2.21	0.2647	1.76	0.1547	1.36	0.0615
		0.007	2.21	0.4636	1.75	0.2712	1.36	0.1076
		0.010	2.20	0.6614	1.75	0.3879	1.36	0.1537

		Hill [13]		Present study

J	η	k _c²	Ra _c	k _c²	Ra _c
+1	0.001	4.9720	0.647667688	4.9720	0.647666602
	0.005	5.1174	3.054321113	5.1175	3.054321508
	0.01	5.2908	5.699734754	5.2900	5.699684893
−1	0.001	4.8990	0.667125786	4.8991	0.667125722
	0.005	4.7525	3.541442825	4.7524	3.541426234
	0.01	4.5617	7.666775544	4.5616	7.666778591

Penetrative convection due to absorption of radiation in a magnetic nanofluid saturated porous layer

Article Category: Research Article

Published Online: Sep 30, 2019

Page range: 129 - 142

Received: Jan 22, 2019

Accepted: May 08, 2019

DOI: https://doi.org/10.2478/sgem-2019-0018

Keywords
Magnetic nanofluids, Penetrative convection, Darcy model, Radiation absorption, Magnetic field

© 2019 Amit Mahajan, Mahesh Kumar Sharma, published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

The values of the kc and Rac for three different boundary conditions.

Comparison of Ra c and k2.

Penetrative convection due to absorption of radiation in a magnetic nanofluid saturated porous layer

Article Category: Research Article

Published Online: Sep 30, 2019

Page range: 129 - 142

Received: Jan 22, 2019

Accepted: May 08, 2019

DOI: https://doi.org/10.2478/sgem-2019-0018

KeywordsMagnetic nanofluids, Penetrative convection, Darcy model, Radiation absorption, Magnetic field

© 2019 Amit Mahajan, Mahesh Kumar Sharma, published by Sciendo

This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 License.

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

The values of the kc and Rac for three different boundary conditions.

Comparison of Ra c and k2.

Keywords
Magnetic nanofluids, Penetrative convection, Darcy model, Radiation absorption, Magnetic field