Comment on Alam et al. Numerical Simulation of Homogeneous–Heterogeneous Reactions through a Hybrid Nanofluid Flowing over a Rotating Disc for Solar Heating Applications. Sustainability 2021, 13, 8289

Mohamed M. Awad

doi:10.3390/su132414044

Mechanical Power Engineering Department, Faculty of Engineering, Mansoura University, Mansoura 35516, Egypt

Sustainability2021, 13(24), 14044;https://doi.org/10.3390/su132414044

This article belongs to the Special Issue Thermal Performance Improvement of Solar Air Heater

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Alam et al. [1] investigated hybrid nanofluid flow with heterogeneous-homogeneous reactions past a rotating disc. They presented the governing equation of temperature (Equation (5) in [1]) as:

[u \frac{\partial T}{\partial r} + W \frac{\partial T}{\partial z}] = {[\frac{k_{h n f}}{{(ρ c_{p})}_{h n f}} + \frac{16 σ^{*} T_{\infty}^{3}}{3 k^{*} {(ρ c_{p})}_{h n f}}]}^{} [\frac{\partial^{2} T}{\partial r^{2}} + \frac{\partial^{2} T}{\partial z^{2}} + \frac{1}{r} \frac{\partial T}{\partial r}]

(1)

From Equation (1), temperature (T) depends on r, z.

Alam et al. [1] used these transformations (Equation (9) in [1]):

η = \sqrt{\frac{Ω}{ν_{f}}} z

(2)

θ (η) = \frac{T (r, z) - T_{\infty}}{T_{w} - T_{\infty}}

(3)

From Equation (2), η depends on z only.

From Equation (3), θ(η) depends on z only because

η = \sqrt{\frac{Ω}{ν_{f}}} z

whereas RHS

\frac{T (r, z) - T_{\infty}}{T_{w} - T_{\infty}}

depends on r, z. Hence, Equation (3) is inappropriate.

Pantokratoras [2,3,4,5,6] indicated that the θ(η) expression is inappropriate. In [6], he presented the correct η form in Minkowycz and Sparrow [7] as:

η = [\frac{g β (T_{w} - T_{\infty})}{4 ν^{2}}] \frac{y}{x^{1 / 4}}

(4)

From Equation (4), η depends on x, y only, which is in agreement with the governing equation of temperature in Minkowycz and Sparrow [7]:

u \frac{\partial T}{\partial x} + v \frac{\partial T}{\partial y} = α \frac{\partial^{2} T}{\partial y^{2}}

(5)

However, Alam et al. [1] expressed their governing equation of temperature (Equation (1) in these comments) as a function of both r, z.

In 2021, Awad [8] indicated that the θ(η) expression is inappropriate.

In their results, Alam et al. [1] presented graphically the various variables effects on the temperature and velocity.

However, many profiles in figures in this paper are truncated and wrong. Pantokratoras [9,10] discussed these common errors. Examples of these figures where profiles are truncated and wrong include:

i: The 3rd figure about ϕ₁ impact on f′(η);
ii: The 10th figure about K_s impact on g(η);
iii: The 11th figure about δ^* impact on g(η).

Funding

This research received no external funding.

Conflicts of Interest

The author declares no conflict of interest.

References

Alam, M.W.; Hussain, S.G.; Souayeh, B.; Khan, M.S.; Farhan, M. Numerical Simulation of Homogeneous–Heterogeneous Reactions through a Hybrid Nanofluid Flowing over a Rotating Disc for Solar Heating Applications. Sustainability 2021, 13, 8289. [Google Scholar] [CrossRef]
Zhao, Q.; Xu, H.; Tao, L.; Pantokratoras, A. Discussion: ‘Homogeneous–Heterogeneous Reactions in Boundary-Layer Flow of a Nanofluid Near the Forward Stagnation Point of a Cylinder,’ (2017, ASME J. Heat Transfer 139(3), p. 034502). ASME J. Heat Transf. 2018, 140, 105501. [Google Scholar]
Pantokratoras, A. Discussion: ‘Three-Dimensional Stagnation Flow and Heat Transfer of a Viscous, Compressible Fluid on a Flat Plate,’ (Mozayyeni, H.R., and Rahimi, A.B., 2013, ASME J. Heat Transfer, 135(10), p. 101702). ASME J. Heat Transf. 2018, 140, 115501. [Google Scholar] [CrossRef]
Pantokratoras, A. Discussion: “Heat and Mass Transfer Analysis in the Stagnation Region of Maxwell Fluid With Chemical Reaction Over a Stretched Surface,” [T. Hayat, M.I. Khan, M. Imtiaz, and A. Alsaedi, 2018, ASME J. Thermal Sci. Eng. Appl., 10(1), p. 011002]. ASME J. Therm. Sci. Eng. Appl. 2019, 11, 015502. [Google Scholar] [CrossRef]
Pantokratoras, A. Discussion: “Double Stratification in Flow by Curved Stretching Sheet With Thermal Radiation and Joule Heating,” [T. Hayat, S. Qayyum, M. Imtiaz, and A. Alsaedi, 2018, J. Therm. Sci. Eng. Appl., 10(2), p. 021010]. ASME J. Therm. Sci. Eng. Appl. 2019, 11, 065502. [Google Scholar] [CrossRef]
Pantokratoras, A. Comment on the paper “Joule heating and viscous dissipation in flow of nanomaterial by a rotating disk, Tasawar Hayat, Muhammad Ijaz Khan, Ahmed Alsaedi, Muhammad Imran Khan, International Communications in Heat and Mass Transfer, 89(2017) 190–197”. Int. Commun. Heat Mass Transf. 2019, 103, 62–63. [Google Scholar] [CrossRef]
Minkowycz, W.J.; Sparrow, E.M. Numerical solution scheme for local nonsimilarity boundary-layer analysis. Numer. Heat Transf. Part B Fundam. 1978, 1, 69–85. [Google Scholar] [CrossRef]
Awad, M.M. Comments on “Dynamism of magnetohydrodynamic cross nanofluid with particulars of entropy generation and gyrotactic motile microorganisms”. Int. Commun. Heat Mass Transf. 2021, 123, 105229. [Google Scholar] [CrossRef]
Pantokratoras, A. A common error made in investigation of boundary layer flows. Appl. Math. Model. 2009, 33, 413–422. [Google Scholar] [CrossRef]
Pantokratoras, A. Four usual errors made in investigation of boundary layer flows. Powder Technol. 2019, 353, 505–508. [Google Scholar] [CrossRef]

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Comment on Alam et al. Numerical Simulation of Homogeneous–Heterogeneous Reactions through a Hybrid Nanofluid Flowing over a Rotating Disc for Solar Heating Applications. Sustainability 2021, 13, 8289

Funding

Conflicts of Interest

References

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