Search

The paper describes an experimental study on the behavior of crib fire with open ventilation conditions. An experimental setup is designed and fabricated in the fire research laboratory, IIT Roorkee to investigate and analyze the crib fire behavior in a compartment. Experiments are carried out in a compartment of the dimension of 4 * 4 * 4 and having a door of 2 * 1(All in meters). The parameters, including the gas temperature, mass loss rate, heat flux, flame temperature, and compartment pressure, were measured during the experiments. Based on experimental results and recognized fire theories, the effect of ventilation conditions on the burning properties of wood cribs was studied.

While extinguishing the fire, firefighters find it difficult to reach certain areas due to narrow spaces or debris blocking the way. In urban cities and industrial areas, there is a constant need to have firefighters ready in case of emergencies. This can lead to a shortage of manpower. Thus, the firefighting robot can act as assisting support for firefighters and will also lower down the risk of their life. Even though many firefighter robots have been developed currently to overcome this problem, these robots are expensive and difficult to maintain. We propose an intelligent robot that uses deep learning to not only detect and classify fire but also extinguish the detected fire based on its class. The proposed firefighter robot is cheaper, autonomous, and easier to maintain. We have used a combination of AlexNet to detect fire and ImageNet for detecting the type of fire. We achieved a classification accuracy of fire detection up to 98.25%, and the classification accuracy of fire-type classification was around 92%. The firefighter robot can be deployed in places that are hard to reach for the firefighters and thereby reduce the burden on firefighters.

An analysis has been carried out to understand the consequences of side-by-side gap-ratio on thermal buoyancy-assisted two-dimensional flow past a pair of heated circular cylinders for a dominant viscous flow field. This is implemented through studies at Reynolds number ( Re) ranging from 5 to 40, Prandtl number ( Pr) 0.7, gap-ratio ( T/D) 1.5 to 4 and Richardson number ( Ri) 0 to 1. An ANSYS-based incompressible flow solver is used with Boussinesq approximation to account for density variations in the momentum equation. One can realize features like the steady-separated and steady-unseparated flow on varying flow and thermal parameters. Unlike streamlines, non-interacting isotherms are non-existent in the current numerical framework. The influence of gap-ratio on enhancement in Nusselt number ( Nu) is the best realized at T/D = 1.5 and buoyancy-aided effects play a dominant role for enhancement in Nu at diffusion and/or viscous-dominant conditions occurring at Re = 5. Correlations are developed to quantify the impact of T/D, Re, and Richardson number Ri on Nu. For the first time, Nu’s correlation based on varying side-by-side gap-ratio has been stated in a single expression. Finally, a comparison for the heat transfer enhancement/reduction in Nu under a similar numerical framework is provided with cases of high-Pr flow and/or different relatable flow arrangements for circular and square cylinders.

Forced convective flow of alumina-water nanofluid with different shapes of nanoparticles through pin-fins of circular cross-section aligned in an equilateral triangular array was analyzed using finite volume methodology. The effect of the shape of alumina nanoparticles on heat transfer across the periodic equilateral triangular array has never been studied in the past. Four different shapes of nanoparticles were considered: spherical, cylindrical, bricks, and platelets. Using non-spherical (cylindrical, bricks, and platelets) nanoparticles resulted in a thinning thermal boundary layer, which resulted in a significant enhancement in heat transfer rates across the array. The mean Nusselt number was augmented by 22% when platelet shaped nanoparticles were utilized in place of spherical shaped nanoparticles. Likewise, the mean Nusselt number was augmented by 17% when cylindrical nanoparticles were used, in place of spherical nanoparticles, at the highest values of other parameters. The increment in effective viscosity of the nanofluid was the highest for platelet-shaped nanoparticles, which resulted in a greater pressure drop compared to other shapes of nanoparticles such as cylindrical, bricks, and spherical for all values of particle concentration. The results in the present article are validated extensively with accessible experimental and numerical studies.

PurposeThis paper delineates the distinctive nature of appraisal politics perceptions (referenced to organizational politics) experienced by appraisees (APAP) as a form of hindrance work stressor that is more episodic than chronic, salient during the PA rating and reward decisions. The study argues and attempts to establish empirically that due to its distinct nature, it causes both short-term episodic strain and long-term chronic strain. Further, the study investigates the distinctive role played by appraisee's hard and soft influence behaviour as a coping mechanism moderating the influence of APAP as a stressor on strain variables in Indian organizational context that ferments politics.Design/methodology/approachThe data was collected using self-reports from 407 employees in Indian organizations using survey method. Multivariate analyses including moderating tests were used for testing the hypotheses.FindingsOnly the episodic components of the APAP-appraiser's rating politics and pay and promotion politics were significantly related to anxiety felt by appraisees during PA – an episodic measure of strain. All three APAP components were significantly related to the chronic strain measure of dissatisfaction. There was modest support for the role of influence tactics (IT) as a coping mechanism attenuating the negative relation of APAP with the dissatisfaction variables as chronic strain measures. Contrary to the hypothesis, softer tactics exacerbated the APAP–PA anxiety relation, indicating the episodic nature of stressor and strain.Originality/valueThe study contributes significantly to enhance the understanding about the nature of Appraisal politics.

The flow of hybrid alumina–copper/water nanofluid with mixed convection heat transfer from multiple square cylinders arranged in three different types of arrays, namely equilateral triangle (ET), rotated square (RS), and rotated rhombus (RR) in a heat exchanger, has never been studied before the present study. Navier–Stokes and energy equations with a periodic boundary condition in the transverse direction for all three array types having the same porosity are solved with the finite volume methodology. The combined effect of aiding buoyancy (Richardson number 0–2), the configuration of square cylinders, and hybrid nanoparticle volume fraction (0-0.06) on the flow dynamics and their impact on the overall heat transfer phenomenon through three different array configurations is thoroughly elucidated. The arrays’ overall drag and friction coefficient increases with an increase in the strength of aiding buoyancy and nanoparticle volume fraction. An increment in Richardson number, and nanoparticle volume fraction, causes thermal boundary layer thinning and results in higher heat transfer rates across all three arrays. With an increase in Ri from 0 to 2 at a nanoparticle volume fraction of 0.06, the mean Nusselt number of ET, RS, and RR arrays is increased by 161%, 5%, and 32%, respectively. While, with an increase in nanoparticle volume fraction from 0 to 0.06 at Ri = 2, the mean Nusselt number of ET, RS, and RR arrays is augmented by 17%, 6%, and 9%, respectively. Finally, the efficient array configuration in terms of fluid-thermal behavior is proposed to design various heat-exchange systems under differing operating conditions.

The article examines the consequence of thermal buoyancy-driven cross-flow and heat transfer for shear-thinning power-law fluids on the tandem orientation of two cylinders. Finite volume methodology is used to investigate the effect of the gap ratio (2.5 ≤ S/D ≤ 5.5), power-law index (0.2 ≤ n ≤ 1), and Richardson number (0 ≤ Ri ≤ 1) on flow and thermal output parameters at Reynolds number Re = 100 and Prandtl number Pr = 50 in a confined channel. An unprecedented jump has been witnessed in the flow/thermal parameters at the critical gap ratio (critical spacing). At forced convection (Ri = 0), this critical spacing keeps on increasing with shear-thinning character, from S/D = 3.9 (at n = 1) to 4.9 (at n = 0.2). On the contrary, an increase in shear-thinning characteristic leads to a decrease in critical spacing from S/D = 3.9 (at n = 1) to 2.8 (at n = 0.4) for Ri = 1 (mixed convection). The heat transfer rate increases with shear-thinning behavior, with a maximum heat transfer, noted at n = 0.2. A higher unprecedented increment for flow/thermal parameters is seen at critical spacing for the downstream cylinder than the upstream cylinder. At the highest gap ratio, the output parameters for the upstream cylinder approximate that of an isolated cylinder. The time-variant fluctuations in lift coefficients for a shear-thinning flow in a tandem arrangement provide a new understanding of coshedding and extended body flow regimes.

n experimental study has been conducted, in a cubical compartment having internal dimensions of 4.0 m length by 4.0 m width by 4.0 m height, to explore the impact of sudden door opening on the burning behavior of burning cribs. Several parameters were measured, such as the mass loss rate, the gas temperature, the centerline flame temperature, the intensity and distribution of heat flux within the compartment boundaries and the compartment pressure. The experimental results indicated that the sudden door opening has a significant impact on the mass loss rate of the crib. As the time of sudden door opening provided to the compartment increases, the peak mass loss rate decreases. The maximum increase in the mass loss rate was 86%, 116% and 154% for Test B, Test C and Test D, respectively. The compartment pressure, gas temperature, flame temperature and heat flux have significant increase due to sudden door opening; however, the heat flux at lower zone has seen a steep decrease.

Hydrodynamic and thermal features of two-dimensional, incompressible shear-thinning and shear-thickening non-Newtonian power-law liquids under forced convection across a trapezoidal cylinder are the focus of this study, carried out at Reynolds number Re = 1–40, power-law index n = 0.4–1.8 and Prandtl number Pr = 50 using ANSYS Fluent. In this steady system, the drag coefficient is found to decrease, whereas the wake size and the average Nusselt number increase with the increase in Re. However, with the increase in n value, the average Nusselt number decreases. Similar to a square cylinder, compared to Newtonian liquids, shear-thinning liquids increases heat transfer and shear-thickening reduces it. The maximum increase in heat transfer for shear-thinning liquids compared to Newtonian liquids for a trapezoidal cylinder is approximately 25%, while the average heat transfer is somewhat lower for shear-thickening liquids than for Newtonian. The average Nusselt number is smaller for the trapezoidal cylinder than for a square cylinder in the parameter domain investigated; the largest difference is around 25%. A simple relationship for the average Nusselt number as a function of Re and n has been determined.

Data on managerial compensation, past performance ratings, and human capital variables (specifically education and work experience) from a manufacturing unit in India were explored in order to explain the variation in total and budgeted variable compensation. The results obtained provide support for the influence of human capital as well as performance variables on compensation. Human capital variable (specifically education) probably impacted compensation structure through market value in a way that could be dubbed elitist. There was some reflection of tournament view also (more differential for higher designation) on compensation. Keywords: Compensation, Incentive design, Pay for performance, Variable pay, Managerial compensation, Compensation management

Aiding buoyancy mixed convection features of Newtonian fluids across a periodic array of heated cylinders have been studied numerically using a commercial CFD solver ANSYS FLUENT. The governing equations have been solved for the following ranges of physical parameters: Reynolds (1 ≤ Re ≤ 40), Prandtl (0.70 ≤ Pr ≤ 50) and Richardson (0 ≤ Ri ≤ 2) numbers and fluid volume fractions of 0.70–0.99. Qualitatively, the dense and curved streamlines and isotherms were seen with the increasing inertial (Re), viscous diffusion (Pr) and buoyancy parameter (Ri) across all the fluid volume fractions. The drag coefficients were observed to be diminished with an upturn in Re and fluid volume fractions, whereas an opposite behavior was noticed with rising in Pr and buoyancy parameter. The Nusselt numbers were found to be enhanced with Re and Pr numbers and moreover with fluid volume fractions also as in contrast to forced convection (Ri = 0) cases. Aiding buoyancy enhances flow as well as heat transfer features and yields unsteady behavior also at the higher fluid volume fractions and Re for all the values of Pr and Ri numbers. Moreover, statistical correlations have been developed for the total drag coefficient and average Nusselt number to gain the more physical insight of the results. Lastly, the findings have been compared with the literature which displayed the good agreement within the ranges of parameters studied herein.

The current research focuses on the laminar flow through permeable side-by-side bars of a square cross section in a channel-confined domain. Vorticity generation on the leeward sides of the permeable bodies further necessitates the study for a better understanding of underlying physics. Reynolds number (Re) and Darcy number (Da) are varied from 5 to 150 and 10−6 to 10−2, respectively, at transverse gap ratios s/d = 2.5–10. In the perspective of periodic unsteady flow, critical Re for the onset of vortex shedding is analyzed. Streamlines, vorticity, pressure coefficient distribution, and velocity profiles are discussed to identify the wake patterns. In lower permeability level, vortex-shedding from the permeable square cylinders is observed either in synchronized antiphase mode or a single large vortex street with a synchronized in-phase pattern in the near wake. A steady-state wake pattern symmetric and flocked toward the centerline is observed for all s/d at a higher permeability level regardless of Re. Wake patterns are not altered for Da = 10−6 to 10−3; instead, prompt extermination of the two vortex streets downstream is observed at Da = 10−3 as compared to Da = 10−6. The impact of s/d, Re, and permeability on the drag is examined. A jump in the flow characteristics and drag forces is noticed at higher Re for the midrange Da remarkably at lower s/d. For the extent of high permeability, the drag coefficient asymptotically gets closer to zero.

The flow of alumina–water nanofluid across heated circular tubes arranged in inline and staggered arrays in a heat exchanger has been studied numerically using the finite volume method (FVM). For calculating the nanofluid’s thermophysical properties such as effective thermal conductivity and effective viscosity, Corcione’s correlations are utilized. Corcione’s correlations consider nanoparticles size, their Brownian motion, and operating temperature while calculating these effective properties of nanofluids. The impact of three parameters on heat transfer characteristics across inline and staggered arrays of heated circular cylinders has been examined. These parameters are nanoparticle diameter dp, which is varied between 10 nm and 50 nm, nanoparticle volume fraction ɸ varying from 0.01 to 0.05, and Reynolds number Re ranging from 10 to 200. It is observed that heat transfer augmentation across both inline and staggered arrays occurs when nanoparticle concentration is increased and smaller diameter nanoparticles are used. Mean Nusselt number NuM is increased by 31% when ɸ is increased from 0.01 to 0.05 at Re = 200 and dp = 10 nm in an inline array and by 25% in a staggered array. NuM is enhanced by 20% for the inline array and 16% for the staggering array when dp decreases from 50 nm to 10 nm at Re = 200 and ɸ = 0.05. At any given value of dp, ɸ, and Re, the mean Nusselt number is always higher for staggered array in comparison with the inline array. The results reported in the present study can be utilized for the optimal design of various heat exchange systems under the given operating conditions. The present results are extensively validated with the available experimental/numerical studies.

Introduction: Cytogenetics has become an integral part of Multiple Myeloma (MM) diagnosis and prognostication. A combination of conventional cytogenetics and interphase Fluorescence In Situ Hybridization (FISH) is currently used to stratify tumours into high, intermediate and standard risk disease. Aim: To compare the morphological details of plasma cells with cytogenetic abnormalities. Materials and Methods: The present retrospective cross sectional study was conducted at Department of Pathology Dayanand Medical College and Hospital, Ludhiana in three and a half year duration (1st January 2014 to 30th June 2017). All the diagnosed MM patients in whom cytogenetic was available were included and descriptive analysis was done using Chi-Square test and relevant statistical analysis using SPSS 21 version. Correlation was done with various morphological pattern (plasmacytic, plasma blastic). Results: Cytogenetic studies were performed on 42 cases using FISH technique (n=31, 81.6%) and GTG (Giemsa) banding (n=4, 10.5%). Three (7.9%) patients were tested with both methods. In the present study, all the patients (n=2,100%) with plasmablastic morphology who got tested with cytogenetics had del13q14.3 and none of the patients with normal genome (n=22) had plasmablastic morphology. Conclusion: Morphologic patterns of plasma cells and cytogenetic studies correlate well and can together help in better prognostication of MM patients.

Laminar heat transfer characteristics of non-Newtonian power-law fluids from a long (heated) triangular prism in the time-periodic regime have been explored. Momentum and energy equations were solved using finite volume methodology over the range of non-dimensional control parameters: Reynolds number (Re) = 50–150, Prandtl number (Pr) = 1–50 and power-law index (n) = 0.4–1.8. For the fixed Pr, the local and the time-averaged Nusselt numbers increase with rising Re irrespective of n. However, the local and the time-averaged Nusselt numbers decrease as the fluid nature alters from pseudo-plastic (n 1) for the fixed Re and Pr. Maximum enhancements in the values of time-averaged Nusselt numbers for Pr = 10, 20 and 50 with respect to Pr = 1 are observed to be approximately 180, 273 and 438%, respectively. Further, it is observed that for the fixed n and Pr, the Colburn heat transfer factor (or the jh factor) decreases with rising Re. Finally, the various values of the jh factor at different Re, n and Pr have been correlated via a simple expression, thus enabling its estimation in a new application.

Flow around an isolated generic sharp-edged object with varying height ratio (β = 0–1) i.e. height from the rear end of the object to the front end ( β = H 2 / H 1 ) has been investigated in cross-flow configuration covering steady and periodic regimes at Reynolds number (Re) from 1 to 150 using air as a working fluid. Flow separation is delayed with a decrease in β. Wake formed is the highest for β = 1 (square object) and progressively decreases with the decrease in β. The vortex shedding effect has been demonstrated on the heat transfer phenomena around the objects. For all the cases of height ratios, as Re increases the flow undergoes supercritical Hopf bifurcation to periodic state as steady-state condition loses its stability. Stuart-Landau theory has been used to determine the value of critical Re or the onset of vortex shedding for all the cases of height ratios. As β increases from 0 to 0.7, the value of critical Re increases. Influence of surface vorticity and surface pressure on the overall drag coefficient ( C D ) has been explored. Effect of β on the Strouhal number (St) has been investigated and the findings are in agreement with previous results. Finally, correlations relating Lr, C D , Nu ‾ and St with Re and β have been developed.

Numerical computations were brought up to study the effect of opposing buoyancy mixed convection (Ri = 0 to − 1) flow of power law shear-thinning fluids past a confined cooled square bluff body at ...

Assessment of heat release rate in a compartment fires is a major concern for fire investigators to predict the fire behavior. The fire experiment was conducted in a cubical compartment of 64 m−3 with a door opening provided at one of the wall. Using the fundamental energy balance equation, an attempt has been made to determine the heat release rate for various interval of time. Instrumentations were made to measure several parameters which include the compartment gas temperature, the velocity and temperature of outgoing gas, heat flux to the compartment boundaries and the heat release rate of the burning crib. Analyzing the results, it was determined that major portion of the energy release during fire went to heat the compartment boundaries followed by energy loss through compartment door opening and energy goes to heat up the gases in the compartment. Nearly 54% of the energy went to heat compartment boundaries, 25% of the energy loss due to outflow of hot gases through door opening, 16% of energy went to heat the compartment gases and 5% of energy dissipated from the door in for of radiation.

A numerical analysis was carried out to examine the effect of pulsating flows around a semi-circular (heated) cylinder placed in a horizontal confined empty channel. The heat transfer induced as an outcome of non-zero mean sinusoidally varying flow past a semi-circular cylinder was investigated. For this purpose, computations are carried out for the following range of parameters: wall confinement (or blockage ratio, β) = 25%; Prandtl number (Pr) = 7 (water as a working fluid); Reynolds number (Re) = 10–100; Strouhal number (St) = 0–2; and amplitude of oscillation (A) = 0–0.6. The current situation is numerically investigated by solving the continuity, momentum and energy equations using the finite volume method—based solver Ansys Fluent. Results in terms of total drag coefficient and Nusselt number have been presented and discussed. The nature of flow for each considered case is reported. The flow (streamlines) and thermal (isothermal contours) patterns have been analyzed. The maximum augmentations of about 22 and 10% were obtained in drag coefficient and Nusselt number, respectively. It is noteworthy that amongst all the cases studied, an appreciable amount of augmentation is observed when St = 1 and A = 0.6 (with respect to the case of non-pulsating flow i.e. St = 0).

The deep learning algorithms and robotics have emerged in each and every field of human life. Most of the recent innovations in image recognition are dependent on deep learning technology. In this manuscript, we present an intelligent robot that uses this deep learning to detect and classify fire. We have used a combination of Alexnet to detect fire and Imagenet for detecting the type of fire. We found out that the classification accuracy of fire detection goes up to 98.25 %. and classification accuracy of firetype classification was around 92 %. We believe that there is a lot of scope to improve the accuracy in firetype classification but could be a good starting point to design robots as per the class of fire with machine vision.

The focus of the current numerical investigation is to study the fluid flow and mixed convective (thermal cross-buoyancy) heat transfer of incompressible fluid across identical cylinders organized in a confined tandem configuration because of their enormous engineering and industrial applications such as heat exchange tubes, electronic cooling, twin chimney stacks, cooling tower, etc. The involved flow and energy equations are solved for different gap ratios (S/D = 2.5, 3, 3.5, 4, 5, and 5.5) with varying Richardson number (Ri = 0, 0.5, and 1) at Reynolds number Re = 100, Prandtl number Pr = 0.7 and wall confinement β = 25% by using a finite volume method-based commercial solver ANSYS Fluent. It is found that after a certain gap ratio there is a drastic change in the physical parameters and after that gap ratio the change is gradual; this gap ratio is termed as a critical gap ratio. The introduction of thermal cross-buoyancy (Ri > 0) plays a deep impact on the physical parameters, and it is to be noted that the critical spacing shifts towards a lower value with increasing Ri. The analysis of lift coefficients shows that the fluctuations in lift signal shift from zero average value at Ri = 0 towards the nonzero negative average value for the tandem cylinders at Ri > 0. The local Nusselt number shows the shift in the front stagnation point on both cylinders with increasing thermal cross-buoyancy. The drag coefficient and Nusselt number of the downstream cylinder are always less than the upstream cylinder, but the percentage increment in the physical parameters of the downstream cylinder after critical spacing is much more than its upstream counterpart.

This work is an attempt to simulate the effects of pulsating flow upon the thermal and hydrodynamic behavior of shear-thinning non-Newtonian fluid (approximated as power-law fluid) while it flows past a semi-circular cylinder fixed in a symmetrically confining channel and deduces the optimum oscillating frequencies and amplitude for a particular power-law index (n) and Reynolds number (Re). The semi-circular cylinder studied has a fixed temperature while the wall confinement is insulating. The ranges of control parameters varied are ${\rm Re}=10$ -100 (based on object's diameter), the amplitude of oscillation (A) = 0-0.6, the Strouhal number (St) = 0-2 and the n ranging from 0.2 to 1. The Prandtl number has been kept fixed at $({\rm Pr})=50$ (which corresponds to several fluids of industrial importance like n-butanol, etc.). The isotherms and streamlines give a qualitative insight into the heat and flow transfer behavior as various parameters are varied, while the Nusselt number, overall drag and lift coefficients have been calculated to get a quantitative insight. Further, the augmentation in heat transfer and the decline in drag upon using a pulsating non-Newtonian fluid inlet as opposed to using a steady Newtonian flow have been established. Lastly, the temporal variations and the frequency of vortex shedding have been studied using a fast Fourier transform.

A fire tests using plywood crib as fire source was done in a cubical compartment to investigate the fire development and temperature distribution. The dimension of the experimental compartment was 4 m high, 4 m wide and 4 m length with a door opening of 2 m × 1 m wide located at one of the compartment wall. Several parameters were measured which includes fuel mass loss rate, compartment gas temperature, centerline doorway temperature, heat flux and wall surface temperature. Three-dimensional numerical simulations were performed using large eddy simulation with different values of Smagorinsky sub-grid scale constant. In order to accurately investigate the behavior of fire within the compartment by computational fluid dynamics (CFD), it is vital to study these Smagorinsky sub-grid scale constant. Numerically predicted results with various Smagorinsky sub-grid scale constant was compared with the physical results. It was found that the varying the Smagorinsky constant affect the numerical simulation results.

An experimental investigation on burning behavior of fire in closed compartments is presented. Fire experiments were performed in a closed compartment of interior dimensions 4 × 4 × 4 m (length × width × height) with ply board cribs as fire source. The parameters including the gas temperature, mass loss rate, heat flux, flame temperature and compartment pressure were measured during the experiments. Experimental results indicated that the providing sudden ventilation to the closed compartment had great influence on the behavior of fire. The mass loss rate of the burning crib increased by 150 % due to sudden ventilation which results in the increase in heat release rate by 198 kW. From the perspective of total heat flux, compartment pressure and gas temperatures closed compartment with sudden ventilation were more hazardous.

Flow and heat transfer characteristics around a semi-circular cylinder placed in a confined channel are investigated in the unsteady regime. The two-dimensional simulations are carried out for varying values of control parameters: Reynolds number (Re) = 50–200 and Prandtl number (Pr) = 0.7, 10 and 100 at a fixed blockage ratio of 25% for Newtonian constant-property fluid. Continuity, Navier–Stokes and energy equations with appropriate boundary conditions are solved using the commercial computational fluid dynamics solver Ansys Fluent. The transition from steady to time-periodic flow occurs between Re = 69 and 70. The effect of Prandtl number on Nusselt number is pronounced; the ratio of Nusselt number values belonging to Pr = 100 and those belonging to Pr = 0.7 ranges from 6.3 to 6.5 over the Reynolds number domain investigated. Finally, the present numerical results are used to develop drag coefficient, Strouhal number and Nusselt number correlations.

In a compartment fire, the plume temperatures and velocities are important parameters which are to be investigated. A proper understanding of behavior and temperature of the flame helps fire engineers and researchers deal with the fire situation. A series of four full scale steady state fire experiments were performed in a fire compartment of dimension 4 m × 4 m in plan and 4 m in height to study the vertical temperature profile of a flame. A pure grade of propane gas was supplied to a square burner of size 0.17 m × 0.17 m to create a steady state fire. The centerline vertical temperature rise of the buoyant plume was measured at seventeen different locations with the help of K-type thermocouples and was compared with several correlations available in the literature. The centerline velocities of buoyant plume were also measured and compared with various plume models. The prediction of Alpert (Fire Technol 8:181–195, [11]) and Cox and Chitty (Combust Flame 39:191–209 [10]) model of plume temperature rise and centerline velocities were found to be closer to that of experimental values.

The effects of cross-buoyancy mixed convection from a square cylinder in the proximity of a plane wall are studied for Reynolds number (Re) = 1–100, Richardson number (Ri) = 0–2, and gap ratio (G) = 0.25–1 at Prandtl number (Pr) = 0.7. The flow observed is steady for G = 0.25 and 0.5. The transition from a steady to a time-periodic system is observed for G = 1, and it is found at Re = 56, 60, and 74 for Ri = 0, 1, and 2, respectively. With increasing G and/or Ri, the drag coefficient and average Nusselt number increase for all Re values studied and the lift coefficient decreases with increasing Ri except at Re = 1. Maximum heat transfer augmentation is found about 89% at G = 0.5 (Re = 20, Pr = 0.7, Ri = 0) with respect to the corresponding value at G = 0.25 (Re = 20, Pr = 0.7, Ri = 0). Lastly, the correlations of drag coefficient and heat transfer have been obtained.

Summary An experimental investigation has been carried out for the burning of plywood cribs in a compartment under different ventilation conditions and two different crib patterns. A total of four experiments were conducted. Of them, three experiments were performed: the burning of regular crib pattern for 0%, 10%, and 100% compartment door opening. The fourth experiment was conducted for the staggered crib pattern with 100% door opening. Several measurements were made during experiments that include the flame temperature, ceiling temperature, total heat flux, outgoing gas temperatures, and heat release rate to investigate the burning characteristics and compartment environment. The rate of increase of heat release rate during growth period for staggered pattern crib was 11.5 kW/min, whereas for regular pattern crib, it was 8 kW/min. However, the peak heat release rate was only 15 kW higher as compared with that of the regular pattern crib. Increasing the ventilation to 10% and 100% has resulted in increase in the heat release rate by 61.6% and 77.4%, respectively. The compartment gas temperature and the total heat flux were highest for 10% door opening, whereas no significant changes were observed in flame temperatures with different ventilation conditions as well as crib pattern. Copyright © 2016 John Wiley & Sons, Ltd.

A dielectric fluid plays a significant role on the machining efficiency of Electric discharge machining (EDM). Two phase (liquid-air) dielectric medium was utilized in near-dry (EDM). It is an environmentally friendly process. The present article reports the effect of different dielectric mediums on responses of near-dry EDM. Dielectric mediums used for experimentation were water-air, EDM oil-air and glycerin-air mixtures. The process parameters selected for experimentation were current, duty factor, flushing pressure and lift. Material removal mechanism of near-dry EDM is investigated using imaging techniques. Dielectric fluid with higher viscosity and higher Prandtl number provided better results than fluids with lower viscosity. The results reveal that the Material removal rate (MRR) with glycerin-air dielectric medium is about three-times higher than other dielectric medium used with negligible recast layer. The tool wear rate is negligible in near-dry EDM in relation to all the dielectric mediums.

The influence of opposing-buoyancy mixed convection from a square cylinder in a vertical channel has been studied at Reynolds numbers (Re) = 1–100, Richardson numbers (Ri) = 0 to −1, and blockage ratios (β) = 10–50% for air as a working fluid. The onset of a steady to a time-periodic regime is found for Ri = 0 (at Re = 35, 65, 74, and 62), Ri = −0.5 (at Re = 12, 39, 48, and 54), and Ri = −1 (at Re = 9, 30, 39, and 50) for β = 10%, 25%, 30%, and 50%, respectively. The initiation of flow separation is also determined. Finally, the correlations of Strouhal number, drag coefficient, and the Colburn heat transfer factor were obtained.

Aplastic anemia (AA) is nowadays considered to be a clonal disorder arising from a defective hematopoietic stem cell developing after a generalized insult to bone marrow. Immunosuppressive treatment (IST) of AA causes suppression of the target dominant population of haematopoietic cells allowing the defective non targeted clones to expand. This may give rise to acute leukemia. Cytogenetic studies for chromosomal aberrations such as trisomy and monosomy may help in detecting such conversions. We present a case of acquired AA in a 60-year-old male presenting with pancytopenia and hypoplastic marrow treated with antithymocyte globulin, converting into myelodysplastic syndrome and later on acute promyelocytic leukemia after being in remission for 4 years. The patient was found to have trisomy 8 on fluorescence in situ hybridization and karyotyping.

In this article, investigations have been carried out to decipher the effect of thermal buoyancy in a viscosity stratified flow field for a shear-thinning fluid flowing past a pair of heated side-by-side square cylinders, which is an extension part of our recent study [Sanyal, A. and Dhiman, A., “Wake interactions in a fluid flow past a pair of side-by-side square cylinders in presence of mixed convection,” Phys. Fluids 29, 103602 (2017)]. It is found that the leading-edge flow-separations from the square cylinders influence the near-wake structures and vortex shedding patterns in the presence of shear-thinning effects, which is otherwise missing for Newtonian fluid flow at Reynolds number Re = 40 and Richardson number Ri = 1. The distribution of wall-viscosity η along the inner surfaces of the side-by-side square cylinders, at different values of transverse spacings s/d and flow-behavior indices n, hints at large dependency on the inflections in the velocity profile within the gap-flow region. Under thermal buoyancy-driven mild shear-thinning flow conditions (n = 0.6 and 0.8), the gap-flow characteristics have been classified into “pressure-driven” and “momentum-driven” flow regimes, which provides a good explanation for the aberrations noted in the distribution pattern of η. The root-mean-square fluctuations of the velocity-magnitude and vortex shedding phenomenon are found to reciprocate a consistent flow physics associated with a shear-thinning flow at near and far-field downstream. The single body deflected type flow is primarily seen under predominant shear-thinning flow conditions (n = 0.4), compared to chaotic or quasi-periodic flow under mild shear-thinning conditions. Besides, the evolution of non-linear dynamics-based flow regimes (classified with respect to s/d using power spectrum density analysis) at different values of n and s/d is thoroughly summarized. The time-variant fluctuations of lift and drag force parameters are also found to be unified through cause and effects.

The thermal characteristics of incompressible non-Newtonian power-law fluids across periodic array of circular cylinders have been examined using the finite volume-based numerical solver ANSYS-FLUENT for the following ranges of physical parameters: Reynolds number; 1 ≤ Re ≤ 40: Prandtl number; 1 ≤ Pr ≤ 100: power-law index; 0.40 ≤ n ≤ 1.8; and fluid volume fractions ranging from 0.70 to 0.99. The thermal features have been described via isotherm patterns, local and average Nusselt numbers and the Colburn heat transfer factor and found to be strongly dependent over the above physical parameters. It was observed that the dense isotherms with the increasing inertial and viscous diffusion suggest an improvement in the rate of heat transfer across the periodic cylinders. An increase in local Nusselt number was seen with the increasing values of Re and/or Pr across all the fluid volume fractions. Further, the different behavior of the average Nusselt number was noticed because of the shear-thinning and shear-thickening natures. An enhancement of about 97% was noticed in the shear-thinning region between the extreme fluid volume fractions for the highest value of Pr and the lowest values of Re and n. However, in many cases, the enhancement was noticed to be even more than 100%. An empirical correlation for the average Nusselt number and the Colburn heat transfer factor (jH) has been developed to give the additional physical insight of the results. Finally, the comparison was made with the available literature which displayed a good agreement with the present results.

Numerical computations have been carried out to explore the influence of mixed convection heat transfer from heated trapezoidal geometries of two different configurations namely converging and diverging cylinders in a vertical domain. The recirculation length of the diverging cylinder is found to be more than that of the converging cylinder for all values of Re (5 to 40) considered in this study and this length decreases after introducing buoyancy effect. Drag coefficients decrease with increase in Re for a fixed Ri. However, drag increases for the increasing values of Ri (values considered up to 1). The drag coefficient is found to be the smaller for diverging cylinder than that of converging one. Local Nusselt number shows significant increase as Re and Ri values increase, which results in enhanced heat transfer. Keeping Ri fixed and increasing the value of Re results in the augmentation of heat transfer and is around 15% at Re = 5 and 23% at Re = 40 for Ri = 0 for a square cylinder with respect to diverging cylinder. Under the influence of aiding buoyancy, the values of average Nusselt number ( $$ \overline{Nu} $$ ) for the diverging cylinder are higher compared to that of converging cylinder. A correlation expressing functional relationship of $$ \overline{Nu} $$ with Re and Ri has also been generated.

The laminar flow and heat transfer across a triangular periodic array of heated cylinders are simulated computationally and analyzed. The study has been carried out at Reynolds number 10–100 for fluid volume fraction ranging from 0.7 to 0.99 and Prandtl number ranging from 0.7 to 50. The size of the wake region increases continuously with an increase in the Reynolds number for all values of fluid volume fraction. The recirculation bubble from the rear of a cylinder is reaching the front of the next cylinder in the same column of the periodic array for low values of free volume fraction, but this is not the case with the highest free volume fraction, i.e., 0.99. At high Reynolds number, the flow is separating early on the cylinder surfaces. The wake size at higher Reynolds number 75 and 100 for the lowest free volume fraction 0.7 is more in comparison with the wake size at free volume fraction 0.99, which is explained by plotting the location of flow separation against Reynolds number for both the extreme values of free volume fractions, i.e., 0.7 and 0.99. The isovorticity contours are concentrated in the vicinity of the cylinders on increasing the Reynolds number irrespective of free volume fraction and then convected downstream. On increasing free volume fraction, the friction and pressure drags in the array decrease. The increase in Reynolds number also results in the decrease in the values of the individual (friction and pressure drag coefficients) as well as total drag coefficients for all values of free volume fraction. At high values of Reynolds number, the emergence of carbuncle or thermal spike on isotherm near the cylinder’s surface is observed where the value of the local Nusselt number is observed low. The heat transfer improves and the Nusselt number increases as the Reynolds number and/or Prandtl number increases. On the contrary, heat transfer decreases as free volume fraction increases.