scholarly journals Gravity-driven hydromagnetic flow of couple stress hybrid nanofluid with homogenous-heterogeneous reactions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Muhammad Waseem ◽  
Taza Gul ◽  
Imran Khan ◽  
Arshad Khan ◽  
Anwar Saeed ◽  
...  
Keyword(s):  
Couple Stress ◽  
Heterogeneous Reaction ◽  
Thermal Characteristics ◽  
Heterogeneous Reactions ◽  
Hybrid Nanofluid ◽  
Heated Plate ◽  
Hydromagnetic Flow ◽  
Gravity Driven ◽  
Autocatalytic Kinetics ◽  
The Impact

AbstractThis investigation describes the hydromagnetic flow of gravity-driven couple stress hybrid nanofluid past a heated plate. The carbon nanotubes (CNTs) are used to characterize the hybrid nanofluid. The heated plate is placed vertically with an application of homogenous-heterogeneous reactions to the assumed flow system. The homogeneous reaction governs by isothermal cubic autocatalytic kinetics while the heterogeneous reaction governs by the first order kinetics. For current study the couple stress hybrid nanofluid is presumed to be conducted electrically with impact of non-uniform magnetic effects. An appropriate set of dimensionless quantities has employed to governing equations and then has solved by homotopy analysis method. The influence of emerging parameters encountered in this work has discussed in detail with the help of graphs. In this study it has examined that, flow of fluid reduces with upsurge in magnetic parameter and volumetric concentrations, whereas thermal and concentration characteristics augment with increase in volumetric concentrations. Moreover, growth in Prandtl number leads to a reduction in thermal characteristics and growth in Schmidt number result a reduction in concentration profile. The impact of various emerging parameters has also studied numerically upon physical quantities. It has established that, with augmentation in values of buoyancy parameter there is a growth in the values of skin friction. A comparison has also carried out between current and established results with a fine agreement in both results.

Hybrid nanofluid flow over a stretched cylinder with the impact of homogeneous–heterogeneous reactions and Cattaneo–Christov heat flux: Series solution and numerical simulation

Heat Transfer ◽  
2021 ◽  
Author(s):  
Anthonysamy John Christopher ◽  
Nanjundan Magesh ◽  
Ramanahalli Jayadevamurthy Punith Gowda ◽  
Rangaswamy Naveen Kumar ◽  
Ravikumar Shashikala Varun Kumar
Keyword(s):  
Numerical Simulation ◽  
Heat Flux ◽  
Series Solution ◽  
Heterogeneous Reactions ◽  
Hybrid Nanofluid ◽  
Nanofluid Flow ◽  
The Impact

Theoretical analysis of SWCNT- MWCNT/H2O hybrid flow over an upward/downward moving rotating disk

2021 ◽  
pp. 239779142098028
Author(s):  
R.J. Punith Gowda ◽  
R. Naveenkumar ◽  
J.K. Madhukesh ◽  
B.C. Prasannakumara ◽  
Rama Subba Reddy Gorla
Keyword(s):  
Heterogeneous Reaction ◽  
Three Dimensional ◽  
Rotating Disk ◽  
Heterogeneous Reactions ◽  
Hybrid Nanofluid ◽  
Boundary Constraints ◽  
Wide Range ◽  
Contraction Parameter ◽  
Dimensional Parameters ◽  
Source Sink

The flow-through various disk movement has wide range of applications in manufacturing processes like, computer storage equipment’s, rotating machines, electronic and various types of medical equipment’s. Inspired from these applications, here we scrutinised the consequences of homogeneous-heterogeneous reactions and uniform heat source/sink on the three-dimensional (3D) hybrid SWCNT-MWCNT’s flow on time dependent moving upward/downward rotating disk. The renowned innovation of this paper is the application of the hybrid nanofluid made up of SWCNT and MWCNT’s. Heat generation/absorption effect for the disk that does not move up or down creates a dual flow on the disk. Alternatively, the rotation and upright motion of the disk creates a 3D flow on the surface which has not been considered in the open literature. The modelled PDE’s are reduced in to ODE’s by opting suitable similarity variables and boundary constraints. Here, we used RKF-45 method to obtain the numerical approximations by adopting shooting technique. The analysis of rate of heat transfer is done through graphs. Further, change in velocity, thermal and concentration profiles for various non-dimensional parameters are deliberated briefly and illustrated with the help of suitable plots. The results reveal that, the, rise in values of homogeneous and heterogeneous reaction parameters improve the rate of reaction which results in reduction of the distribution rate and diminishes the concentration gradient. An increase in expansion/contraction parameter enhances the velocity and thermal gradients.

scholarly journals Ozone impacts of gas–aerosol uptake in global chemistry transport models

2018 ◽  
Vol 18 (5) ◽  
pp. 3147-3171 ◽  
Author(s):  
Scarlet Stadtler ◽  
David Simpson ◽  
Sabine Schröder ◽  
Domenico Taraborrelli ◽  
Andreas Bott ◽  
...  
Keyword(s):  
East Asia ◽  
Surface Area ◽  
General Circulation ◽  
Heterogeneous Reaction ◽  
Circulation Model ◽  
Photochemical Reactions ◽  
Heterogeneous Reactions ◽  
Transport Models ◽  
Global Pattern ◽  
The Impact

Abstract. The impact of six heterogeneous gas–aerosol uptake reactions on tropospheric ozone and nitrogen species was studied using two chemical transport models, the Meteorological Synthesizing Centre-West of the European Monitoring and Evaluation Programme (EMEP MSC-W) and the European Centre Hamburg general circulation model combined with versions of the Hamburg Aerosol Model and Model for Ozone and Related chemical Tracers (ECHAM-HAMMOZ). Species undergoing heterogeneous reactions in both models include N2O5, NO3, NO2, O3, HNO3, and HO2. Since heterogeneous reactions take place at the aerosol surface area, the modelled surface area density (Sa) of both models was compared to a satellite product retrieving the surface area. This comparison shows a good agreement in global pattern and especially the capability of both models to capture the extreme aerosol loadings in east Asia. The impact of the heterogeneous reactions was evaluated by the simulation of a reference run containing all heterogeneous reactions and several sensitivity runs. One reaction was turned off in each sensitivity run to compare it with the reference run. The analysis of the sensitivity runs confirms that the globally most important heterogeneous reaction is the one of N2O5. Nevertheless, NO2, HNO3, and HO2 heterogeneous reactions gain relevance particularly in east Asia due to the presence of high NOx concentrations and high Sa in the same region. The heterogeneous reaction of O3 itself on dust is of minor relevance compared to the other heterogeneous reactions. The impacts of the N2O5 reactions show strong seasonal variations, with the biggest impacts on O3 in springtime when photochemical reactions are active and N2O5 levels still high. Evaluation of the models with northern hemispheric ozone surface observations yields a better agreement of the models with observations in terms of concentration levels, variability, and temporal correlations at most sites when the heterogeneous reactions are incorporated. Our results are loosely consistent with results from earlier studies, although the magnitude of changes induced by N2O5 reaction is at the low end of estimates, which seems to fit a trend, whereby the more recent the study the lower the impacts of these reactions.

Three-dimensional flow of radiative hybrid nanofluid past a permeable stretching/shrinking sheet with homogeneous-heterogeneous reaction

2021 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Najiyah Safwa Khashi'ie ◽  
Norihan Md Arifin ◽  
Natalia C. Rosca ◽  
Alin V. Rosca ◽  
Ioan Pop
Keyword(s):  
Heterogeneous Reaction ◽  
Three Dimensional ◽  
Heterogeneous Reactions ◽  
Shrinking Sheet ◽  
Hybrid Nanofluid ◽  
Three Dimensional Flow ◽  
Suction Parameter ◽  
Content Type ◽  
Fluid Concentration ◽  
The Stability

Purpose The purpose of this paper is to study the effects of thermal radiation and homogeneous-heterogeneous reactions in the three-dimensional hybrid nanofluid flow past a permeable stretching/shrinking sheet. Design/methodology/approach The combination of aluminum oxide (Al2O3) and copper (Cu) nanoparticles with total volumetric concentration is numerically analyzed using the existing correlations of hybrid nanofluid. With the consideration that both homogeneous and heterogeneous reactions are isothermal while the diffusion coefficients of both autocatalyst and reactant are same, the governing model is simplified into a set of differential (similarity) equations. Findings Using the bvp4c solver, dual solutions are presented, and the stability analysis certifies the physical/real solution. The findings show that the suction parameter is requisite to induce the steady solution for shrinking parameter. Besides, the fluid concentration owing to the shrinking sheet is diminished with the addition of surface reaction. Originality/value The present findings are novel and can be a reference point to other researchers to further analyze the heat transfer performance and stability of the working fluids.

scholarly journals Ozone Impacts of Gas-Aerosol Uptake in Global Chemistry Transport Models

2017 ◽  
Author(s):  
Scarlet Stadtler ◽  
David Simpson ◽  
Sabine Schröder ◽  
Domenico Taraborrelli ◽  
Andreas Bott ◽  
...  
Keyword(s):  
East Asia ◽  
Surface Area ◽  
Heterogeneous Reaction ◽  
Photochemical Reactions ◽  
Heterogeneous Reactions ◽  
Transport Models ◽  
Global Pattern ◽  
Temporal Correlations ◽  
The One ◽  
The Impact

Abstract. The impact of six heterogeneous gas-aerosol uptake reactions on tropospheric ozone and nitrogen species was studied using two chemical transport models, EMEP MSC-W and ECHAM-HAMMOZ. Species undergoing heterogeneous reactions in both models include N2O5, NO3, NO2, O3, HNO3 and HO2. Since heterogeneous reactions take place at the aerosol surface area, the modeled surface area density Sa of both models was compared to a satellite product retrieving the surface area. This comparison shows a good agreement in global pattern and especially the capability of both models to capture the extreme aerosol loadings in East Asia. The impact of the heterogeneous reactions was evaluated by the simulation of a reference run containing all heterogeneous reactions and several sensitivity runs. One reaction was turned off in each sensitivity run to compare it with the reference run. The analysis of the sensitivity runs confirms that the globally most important heterogeneous reaction is the one of N2O5. Nevertheless, NO2, HNO3 and HO2 heterogeneous reaction gain relevance particularly in East Asia due to the presence of high NOx concentrations and high Sa in the same region, although ECHAM-HAMMOZ showed much stronger responses than EMEP in this respect. The heterogeneous reaction of O3 itself on dust is of minor relevance compared to the other heterogeneous reactions. The impacts of the N2O5 reactions show strong seasonal variations, with biggest impacts on O3 in spring time when photochemical reactions are active and N2O5 levels still high. Evaluation of the models with northern hemispheric ozone surface observations yields a better agreement of the models with observations in terms of concentration levels, variability, and temporal correlations at most sites when the heterogeneous reactions are incorporated.

scholarly journals Heterogeneous reaction of HO<sub>2</sub> with airborne TiO<sub>2</sub> particles and its implication for climate change mitigation strategies

2017 ◽  
Author(s):  
Daniel R. Moon ◽  
Giorgio S. Taverna ◽  
Clara Anduix-Canto ◽  
Trevor Ingham ◽  
Martyn P. Chipperfield ◽  
...  
Keyword(s):  
Transport Model ◽  
Heterogeneous Reaction ◽  
Three Dimensional ◽  
Mitigation Strategies ◽  
Heterogeneous Reactions ◽  
Chemical Transport Model ◽  
Flow Tube ◽  
Tio2 Particles ◽  
The Impact ◽  
Change Mitigation

Abstract. One geoengineering mitigation strategy for global temperature rises resulting from the increased concentrations of greenhouse gases is to inject particles into the stratosphere to scatter solar radiation back to space, with TiO2 particles emerging as a possible candidate. Uptake coefficients of HO2, γ(HO2), onto sub-micrometre TiO2 particles were measured at room temperature and different relative humidities (RH) using an atmospheric pressure aerosol flow tube coupled to a sensitive HO2 detector. Values of γ(HO2) increased from 0.021 ± 0.001 to 0.036 ± 0.007 as the RH was increased from 11 % to 66 %, and the increase in γ(HO2) correlated with the number of monolayers of water surrounding the TiO2 particles. The impact of the uptake of HO2 onto TiO2 particles on stratospheric concentrations of HO2 and O3 was simulated using the TOMCAT three-dimensional chemical transport model. The model showed that by injecting the amount of TiO2 required to achieve the same cooling effect as the Mt. Pinatubo eruption, heterogeneous reactions between HO2 and TiO2 would have a negligible effect on stratospheric concentrations of HO2 and O3.

scholarly journals Modeling the impact of heterogeneous reactions of chlorine on summertime nitrate formation in Beijing, China

2019 ◽  
Vol 19 (10) ◽  
pp. 6737-6747 ◽  
Author(s):  
Xionghui Qiu ◽  
Qi Ying ◽  
Shuxiao Wang ◽  
Lei Duan ◽  
Jian Zhao ◽  
...  
Keyword(s):  
Heterogeneous Reaction ◽  
Particle Surface ◽  
Heterogeneous Reactions ◽  
Sensitivity Analyses ◽  
Uptake Coefficient ◽  
Transport Models ◽  
Nitrate Concentrations ◽  
The Impact ◽  
Beijing China ◽  
Significant Underestimation

Abstract. Comprehensive chlorine heterogeneous chemistry is incorporated into the Community Multiscale Air Quality (CMAQ) model to evaluate the impact of chlorine-related heterogeneous reaction on diurnal and nocturnal nitrate formation and quantify the nitrate formation from gas-to-particle partitioning of HNO3 and from different heterogeneous pathways. The results show that these heterogeneous reactions increase the atmospheric Cl2 and ClNO2 level (∼ 100 %), which further affects the nitrate formation. Sensitivity analyses of uptake coefficients show that the empirical uptake coefficient for the O3 heterogeneous reaction with chlorinated particles may lead to the large uncertainties in the predicted Cl2 and nitrate concentrations. The N2O5 uptake coefficient with particulate Cl− concentration dependence performs better in capturing the concentration of ClNO2 and nocturnal nitrate concentration. The reaction of OH and NO2 in the daytime increases the nitrate by ∼15 % when the heterogeneous chlorine chemistry is incorporated, resulting in more nitrate formation from HNO3 gas-to-particle partitioning. By contrast, the contribution of the heterogeneous reaction of N2O5 to nitrate concentrations decreases by about 27 % in the nighttime, when its reactions with chlorinated particles are considered. However, the generated gas-phase ClNO2 from the heterogeneous reaction of N2O5 and chlorine-containing particles further reacts with the particle surface to increase the nitrate by 6 %. In general, this study highlights the potential of significant underestimation of daytime concentrations and overestimation of nighttime nitrate concentrations for chemical transport models without proper chlorine chemistry in the gas and particle phases.

scholarly journals Heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> with airborne TiO<sub>2</sub> particles and its implication for stratospheric particle injection

2014 ◽  
Vol 14 (4) ◽  
pp. 4421-4456 ◽  
Author(s):  
M. J. Tang ◽  
P. J. Telford ◽  
F. D. Pope ◽  
L. Rkiouak ◽  
N. L. Abraham ◽  
...  
Keyword(s):  
Solar Radiation ◽  
Climate Model ◽  
Heterogeneous Reaction ◽  
High Refractive Index ◽  
Heterogeneous Reactions ◽  
Solar Radiation Management ◽  
Particle Injection ◽  
Stratospheric Chemistry ◽  
Radiation Management ◽  
The Impact

Abstract. Injection of aerosol particles (or their precursors) into the stratosphere to scatter solar radiation back into space, has been suggested as a solar-radiation management scheme for the mitigation of global warming. TiO2 has recently been highlighted as a possible candidate particle because of its high refractive index, but its impact on stratospheric chemistry via heterogeneous reactions is as yet unknown. In this work the heterogeneous reaction of airborne sub-micrometre TiO2 particles with N2O5 has been investigated for the first time, at room temperature and different relative humidities (RH), using an atmospheric pressure aerosol flow tube. The uptake coefficient of N2O5 onto TiO2, γ(N2O5), was determined to be ∼ 1.0 × 10−3 at low RH, increasing to ∼ 3 × 10−3 at 60% RH. The uptake of N2O5 onto TiO2 is then included in the UKCA chemistry climate model to assess the impact of this reaction on stratospheric chemistry. While the impact of TiO2 on the scattering of solar radiation is chosen to be similar to the aerosol from the Mt. Pinatubo eruption, the impact of TiO2 injection on stratospheric N2O5 is much smaller.

scholarly journals Darcy–Forchheimer couple stress hybrid nanofluids flow with variable fluid properties

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Anwar Saeed ◽  
Poom Kumam ◽  
Taza Gul ◽  
Wajdi Alghamdi ◽  
Wiyada Kumam ◽  
...  
Keyword(s):  
Differential Equations ◽  
Couple Stress ◽  
Variable Viscosity ◽  
Current Model ◽  
Hybrid Nanofluid ◽  
Mean Velocity ◽  
Homotopy Analysis ◽  
Fluid Properties ◽  
Hybrid Nanofluids ◽  
The Impact

AbstractThe current study provides a detailed analysis of steady two-dimensional incompressible and electrically conducting magnetohydrodynamic flow of a couple stress hybrid nanofluid under the influence of Darcy–Forchheimer, viscous dissipation, joule heating, heat generation, chemical reaction, and variable viscosity. The system of partial differential equations of the current model (equation of motion, energy, and concentration) is converted into a system of ordinary differential equations by adopting the suitable similarity practice. Analytically, homotopy analysis method (HAM) is employed to solve the obtained set of equations. The impact of permeability, couple-stress and magnetic parameters on axial velocity, mean critical reflux condition and mean velocity on the channel walls are discussed in details. Computational effects show that the axial mean velocity at the boundary has an inverse relation with couple stress parameter while the permeability parameter has a direct relation with the magnetic parameter and vice versa. The enhancement in the temperature distribution evaluates the pH values and electric conductivity. Therefore, the $$SWCNTs\,\,{\text{and}}\,\,MWCNTs$$ S W C N T s and M W C N T s hybrid nanofluids are used in this study for medication purpose.

scholarly journals Modeling the impact of heterogeneous reactions of chlorine on summertime nitrate formation in Beijing, China

2018 ◽  
Author(s):  
Xionghui Qiu ◽  
Qi Ying ◽  
Shuxiao Wang ◽  
Lei Duan ◽  
Jian Zhao ◽  
...  
Keyword(s):  
Nitrate Concentration ◽  
Heterogeneous Reaction ◽  
Heterogeneous Reactions ◽  
Sensitivity Analyses ◽  
Uptake Coefficient ◽  
Transport Models ◽  
Nitrate Concentrations ◽  
The Impact ◽  
Beijing China ◽  
Significant Underestimation

Abstract. A comprehensive chlorine heterogeneous chemistry is incorporated into the Community Multiscale Air Quality (CMAQ) model to evaluate the impact of chlorine-related heterogeneous reaction on diurnal and nocturnal nitrate formation and quantify the nitrate formation from gas-to-particle partitioning of HNO3 and from different heterogeneous pathways. The results show that these heterogeneous reactions increase the atmospheric Cl2 and ClNO2 level, leading to an increase of the nitrate concentration by ~ 10 % in the daytime. However, these reactions also lead to a decrease the nocturnal nitrate by ~ 20 %. Sensitivity analyses of uptake coefficients show that the empirical uptake coefficient for the O3 heterogeneous reaction with chlorinated particles may lead to the large uncertainties in the predicted Cl2 and nitrate concentrations. The N2O5 uptake coefficient with particulate Cl− concentration dependence performs better to capture the concentration of ClNO2 and nocturnal nitrate concentration. The reaction rate of OH and NO2 in daytime increases by ~ 15 % when the heterogeneous chlorine chemistry is incorporated, resulting more nitrate formation from HNO3 gas-to-particle partitioning. By contrast, the contribution of the heterogeneous reaction of N2O5 to nitrate concentrations decreases by about 27 % in the nighttime when its reactions with chloriated particles are considered. However, the generated gas-phase ClNO2 from the heterogeneous reaction of N2O5 and chlorine-containing particles further decompose to increase the nitrate by 6 %. In general, this study highlights the potential of significant underestimation of daytime and overestimation of nighttime nitrate concentrations for chemical transport models without proper chlorine chemistry in the gas and particle phases.

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