Viscous Production Research Articles

Analysis of Flow Loss Characteristics of a Multistage Pump Based on Entropy Production

To reveal the internal flow loss characteristics of a multi-stage pump, the unsteady calculation of the internal flow field of a seven-stage centrifugal pump was carried out, and the entropy production theory and Q criterion were utilized to analyze the unsteady flow characteristics of each flow component under different flow rates. The research results show that as the flow rate increases, the entropy production value and the energy loss inside the flow components also increase accordingly. The viscous dissipation entropy production caused by fluid viscosity is very small, and the turbulent dissipation entropy production caused by turbulent fluctuations and wall dissipation entropy production are the main sources of energy loss. The impellers, diffusers, and outlet chamber are the main regions of energy loss in the multistage pump. The entropy production value of the first-stage impeller is significantly higher than that of other impellers, while the entropy production value of the first-stage diffuser is significantly lower than that of other diffusers. Through vortex structure analysis, it is found that the high entropy production regions in the impeller are concentrated in the impeller inlet area, the blade suction surface, and the impeller outlet area.

Rational Design of Droplet Microfluidic Reactors for Controllable Non-Newton Viscous Production of Functional Chitosan Microspheres

Rational Design of Droplet Microfluidic Reactors for Controllable Non-Newton Viscous Production of Functional Chitosan Microspheres

Time-dependent hydromagnetic convective transport upon a vertical perforated sheet with heat production and viscous dissipation effects

This research analysed the theoretical influences of viscous dissipation and heat production on an unstable hydromagnetic free convective transference upon a vertical porous sheet. The converted conservation equations are resolved numerically with suitable boundary conditions by exerting the similarity techniques. Then the coupled ODEs is resolved by inserting the finite difference method (FDM). The influences of the working dimensionless numbers or parameters on the flow, concentration and temperature fields, the mass transmission rate, the coefficient of local skin friction, and the heat transmission rate examined and discussed quantitatively with the aid of graphs. The findings show that as the Eckert number rises, the temperature and fluid velocity both advance along with the heat generation parameter. The f ′ ( 0 ) increases by around 8% and 12% due to uprising amounts of the heat generation parameter from 1.0 to 2.0, and the Eckert number from 0.5 to 2.5, respectively. Growing amounts of the heat generation parameter from 1.0 to 2.0 and Eckert number from 0.5 to 2.5, the heat transmission rate lessens by around 63% and 52%, respectively. The comparable outcomes are good coincided with a published article.

Study on the Influence of Tip Clearance on Cavitation Performance and Entropy Production of an Axial Flow Pump

The clearance existing between the impeller rim and the adjacent shroud within the pump configuration establishes conducive circumstances for the initiation of cavitation. The bubbles generated by cavitation will flow forward with the water, blocking the channel, and result in the degradation of the pump performance. When the cavitation is severe, vibration and noise will be generated. The impact formed by the collapse of the bubbles will seriously erode the blades and form pits on the blade surfaces. Drawing upon the outcomes derived from numerical simulations, this paper investigates the relationship between tip clearance and cavitation in an axial flow pump, with a specific focus on energy dissipation characteristics. The principal findings indicate that the dimensions of the tip clearance predominantly influence the spatial distribution of the tip leakage vortex (TLV) cavitation. The entropy production rate distribution at the tip correlates with both the cavitation level of the pump and the extent of the tip clearance. The shedding phenomenon of the TLV becomes more evident when analyzing the distribution of entropy production rates. During cavitation, an increased tip clearance is associated with a reduction in the dissipation of viscous entropy production within the impeller domain, and the entropy production resulting from turbulent dissipation significantly surpasses that arising from viscous dissipation.

Numerical investigation of hydrothermal performance and entropy production rates of rGO-CO3O4/H2O hybrid nanofluid in wavy channels using discrete phase model

This work investigates numerically the turbulent hydrothermal performance and the entropy production rate (EPR) of rGO-CO3O4/H2O hybrid nanofluid “reduced-graphene oxide/cobalt oxide (rGO-CO3O4) nanoparticle with water as a base fluid” flow in two-dimensional straight, serpentine, and furrowed wavy channels. Both discrete phase and k−ω models were used in ANSYS Fluent package to simulate the turbulent hybrid nanofluid flow based on the finite volume method. The effect of Reynolds number (5.0×103≤Re≤3.0×104), nanoparticle volume ratio (0≤VR≤0.2%), amplitude (0.2≤A*≤0.6), and wavelength (0.7≤λ*≤1.4) on the hydrothermal and EPR were examined. The results revealed that the average Nusselt number (Nu), pressure drop (dP), and EPR due to the viscous dissipation in terms of viscous entropy production rate (VEPR) in wavy channels are higher than that of the straight channel and decrease with increasing λ*. However, the opposite is the case for EPR due to temperature gradient in terms of thermal entropy production rate (TEPR). The normalized (referencing straight channel) dP,Nu, TEPR, and VEPR in the serpentine wavy channel at Re=1.5×104, λ*=0.7 and A* = 0.2 are 16.83, 1.59, 0.76, and 5.93, respectively. The corresponding values at Re=1.5×104, λ*=1.4 and A* = 0.2 are 7.70, 1.34, 0.85, and 3.67, respectively. Furthermore, Nu,dP, and VEPR increase with increasing A*. However, the opposite is the case for TEPR. Finally, the thermal effectiveness number due to geometry modification (Igeo) obtained from combined first and second thermodynamic laws shows that the wavy channels are more effective compared with the straight channel.

Energy loss assessment of a two-stage pump under natural flow in the marine cooling system based on entropy production theory

Natural flow conditions are commonly used in the cooling systems of modern high-speed vessels and nuclear submarines. When the vessel's speed satisfies the requirements, it relies on its kinetic energy to supply seawater to the condenser in the cooling system. Under natural flow conditions, the pump is not driven, and the rotor will be “stuck” or rotated passively by the inlet flow shock. The local energy loss caused by the blade tip leakage vortex, surface separation flow, and wake flow significantly impact the system’s performance. Entropy production is an irreversible dissipation effect caused by the energy transfer process. According to the second law of thermodynamics, the entropy production theory can effectively characterize the intensity of local energy loss under natural flow conditions. In this study, the variation law of hydraulic loss and passive rotational speed under different flow rates of a two-stage pump were obtained by natural flow experiments. Moreover, the generation mechanism of intense energy loss under different natural flow conditions was investigated based on computational fluid dynamics (CFD) and entropy production theory. The results show that the entropy production induced by turbulent kinetic energy (TEP) is dominant, averaging 71.8%, followed by the wall entropy production (WEP), about 26.1%. The contribution of viscous dissipation entropy production (VDEP) can be negligible. When the impeller is “stuck” at low flow rates, entropy production is mainly from the flow separation near the blade and the flow shock region close to the guide vane back. The total entropy production of the guide vane accounts for 78%, higher than the impeller. However, when the impeller rotates passively at high flow rates, the energy loss inside the impeller is dominant, about 62%. The energy loss occurs around the blade wake region and the high velocity-gradient region near the guide vane. The flow field patterns between the two stages are similar, but the energy loss in the impeller and guide vane of stage Ⅱ is much higher. The TEP and WEP of the two impeller stages differed by 14% and 10%, respectively, and the guide vane of the two stages differed by 8% and 3%, at a flow rate of 196.8 m3/h.

Numerical investigation of turbulent entropy production rate in conical tubes fitted with a twisted-tape insert

This paper investigates the turbulent entropy production rate of water flow in convergent and divergent pipes with and without twisted tape inserts for the first time. A carefully validated numerical model was adopted using Ansys-Fluent with k − ε model. The effect of Reynolds number (3 × 103 ≤ Re ≤ 4.5 × 105), diameter ratio (1.0, 1.5, 2.0, 3.0, and 5.0), and the presence of twisted tape inserts on entropy production rate (EPR) were examined. The result shows that the twisted tape insert increases the viscous entropy production rate (VEPR) but reduces the thermal entropy production rate (TEPR). Also, the TEPR is higher in the divergent pipe than in the convergent pipe. However, the opposite is the case for the VEPR. Furthermore, increasing the diameter ratio increases the divergent pipe's TEPR while decreases it in the convergent pipe. The ratio of TEPR in divergent pipe of diameter ratio 3 to a similar one of diameter ratio 1.5 is 1.26. The corresponding value in converging pipes is 0.96. The combination between the conical tube configurations and TT significantly influences the entropy characteristics. Lastly, two new correlations based on response surface methodology were developed to estimate EPR in convergent and divergent pipes with twisted tape inserts. The results show that the Reynolds number, diameter ratio, and interaction between the two are statistically significant to EPR.

Case Study: Oil Production Optimized With Autonomous Inflow Control Devices Offshore Malaysia

_ Advanced well completions have proven to be an effective method of moderating gas breakthrough while producing a thin oil rim when placed in a heterogenous, carbonate reservoir. In addition, several studies have proven that the application of autonomous inflow control devices (AICDs) acts as a type of insurance policy against geological and dynamic reservoir uncertainties to reduce the risk and variation in the expected oil production profiles. During 2019 and 2020, Sarawak Shell Berhad conducted development campaigns in the central Luconia province in a thin oil rim carbonate reservoir offshore Sarawak, Malaysia. The horizontal, approximately 6,000-ft development wells were expected to intersect with different geological layers with varying rock properties, resulting in an uneven reservoir influx toward the wellbore. Oil production from these wells was expected to suffer severely from early gas and water breakthrough. To produce the oil rim without the risk of early gas production, global production optimization specialist, Tendeka, incorporated FloSure AICDs in the lower completion design at the reservoir interface along the horizontal section of the wells. As an active flow control device, the technology delivers a variable flow restriction in response to the properties of the fluid entering the wellbore and the rate of flow passing through it to help manage gas coning/cusping risks. The fluid is then lifted to surface with natural in-situ gas lift built into the upper completion. A three-phase development was planned for the field, and to date, two phases have been completed. New-Generation ICD The first AICD completion was installed in Norway in 2008 and widely implemented in the Troll field in 2013 with very encouraging results (SPE 159634). However, its use is relatively new to both the Asia Pacific region and this type of application. Similar to a standard ICD which balances the influx of reservoir fluids, the FloSure AICD will delay the production of unwanted effluents prior to their breakthrough (proactive solution). However, once a breakthrough occurs, the device restricts the production of unwanted effluents with lower viscosity, such as gas (in light oil applications) and both gas and water in viscous oil production (reactive solution) (OTC 30403, OTC 30363, SPE 193718). The device delivers a variable flow restriction in response to the properties of the fluid and the rate of flow passing through it. Flow enters the device through the nozzle in the top plate of the body. This impacts the disk and spreads radially through the gap between the disk and the top plate, then turns around the top plate and is discharged through several outlet ports in the body (Fig. 1). The overall geometry of the device is critical to its ability to balance these forces effectively and create the desired fluid-dependent pressure drop. Field A employed 7.5-mm AICD valves to match the performance of the devices to the potential well flow rate. The oil, water, and gas viscosities are 0.40 cP, 0.27 cP, and 0.018 cP, respectively, at downhole flow conditions.

Displacement Characteristics and Produced Oil Properties in Steam Flood Heavy Oil Process

Thermal recovery is one of the most effective techniques for viscous oil production, which has been widely used in the heavy oilfield development. The mechanisms and percolation characteristics of thermal recovery have attracted a lot of attention. However, the displacement characteristics and produced oil properties in the steam flood heavy oil process are rarely addressed. In this paper, steam flooding experiments with two heavy oil viscosities under the temperatures from 120 to 200 °C and velocities from 1 to 3 mL/min were carried out to examine the oil displacement efficiency and the produced oil properties. The results show that the majority of the oil is produced in the low water cut stage. Temperature increment is helpful for prolonging the water breakthrough time. The high injection velocity of steam contributes to a high recovery factor, even if it enters into the high water cut stage. The rheology of the produced oils severely changes because the SARA composition changes, and emulsification occurs during the steam flooding heavy oil process. With the increasing steam temperature, the relative content of resins in the produced oils decreases, and asphaltenes increase. With the increase in the injection volume and the injection velocity of steam, the content of resins and asphaltenes increases. This leads to an increment in the produced oil viscosities. The effect of injection velocity on the rheology properties of the produced oils increases with temperature increment. The finding of this work will provide the technical support for heavy oilfields development.

Investigation of turbulent entropy production rate with SWCNT/H2O nanofluid flowing in various inwardly corrugated pipes

AbstractThis paper presents turbulent heat transfer performance and entropy production rate in different inwardly corrugated pipes with single‐walled carbon nanotube (SWCNT)/H2O nanofluid as a working fluid using the finite volume method approach. The configurations considered were circular, triangular, and trapezoidal. The SWCNT/H2O nanofluid was modeled using a single‐phase approach and the model was used to simulate the turbulent flow. A parametric study was carried out on the effect of Reynolds number (5 × 103 ≤ Re ≤ 3 × 104) and nanoparticle volume ratio (0% ≤ φ ≤ 0.25%) on hydrodynamic, heat transfer performance, thermal entropy production rates (TEPRs; due to mean and turbulent temperature gradients), and viscous entropy production rates (VEPRs; due to mean and turbulent velocity gradients). The results showed that the mean temperature gradient contributes most to the TEPR, compared with the turbulent temperature gradient. However, the opposite was the case for the VEPR. Furthermore, the presence of corrugation decreases the TEPR but enhanced friction factor, Nusselt number, and VEPR. For example, at a Reynolds number of 2.5 × 104, the normalized friction factor, average Nusselt number, TEPR, and VEPR (referencing a smooth pipe) in circularly, triangularly, and trapezoidal corrugated pipes are {3.86, 1.39, 0.80, 3.88}, {3.80, 1.41, 0.72, 3.98}, and {4.34, 1.55, 0.69, 4.19}, respectively.

Evaluating of the effect of the cavitation-vortex interaction on the energy conversion in a two-stage LNG cryogenic submerged pump

The quantitative investigation on the unsteady interaction of the thermodynamic cavitation-vortex dynamics has been conducted via the developed entropy production diagnostic model in a two-stage liquefied natural gas cryogenic submerged pump. A thermodynamic cavitation modeling framework and Liutex method are applied to capture the characteristics of the formation, development and collapse of the cavities and vortex. It is found that the increasing flow rate and temperature both intensify the thermodynamic effect of cavitation. As the increase of flow rate, the thermodynamic effect suppresses the growth of cavities, thus raising the maximum temperature drop by 0.65 K at NPSH3% and 0.87 K at NPSH5% with the same temperature. Massive bubbles collapse causes the twist, deformation and breakdown of U-type vortex at the interface, which directly leads to the significant increase of interface entropy production rate in heat transfer entropy production rate (HTEPR). As the increase of temperature, the thermodynamic effect both shortens the cavity size and development period under the same flow rate. The strong shear and rotation regions drive upstream and the pressure rebounds rapidly downstream that weakens the backflow. The shrinkage of upstream cavity and the accelerated collapse of small-scale cloud cavity reduce the HTEPR and viscous flow entropy production rate

Investigation of the entropy production rate of ferrosoferric oxide/water nanofluid in outward corrugated pipes using a two-phase mixture model

This study investigates the turbulent entropy production rate of ferrosoferric oxide/water (Fe3O4/H2O) nanofluid flowing through outward corrugated pipes of different profiles (circular, triangular, and trapezoidal). Both the multi-phase mixture model and the k−ω turbulent model were adopted for simulating the turbulent ferrofluid flow. The effects of Reynolds number (between 5.0 × 103 and 3.0 × 104) and nanoparticle concentration (0.0–3.0%) on viscous entropy production rates (due to mean and turbulent velocity gradients) and thermal entropy production rates (due to mean and turbulent temperature gradient) were examined parametrically. The results show that trapezoidally corrugated pipes tend to have the best heat transfer performance, but also the worst hydraulic performance, where they increase the pressure drop and the average Nusselt number by 2.92 and 1.66 folds, respectively, for a 2.0% nanoparticles’ concentration at Reynolds number of 3.0 × 104. Increasing the concentration of nanoparticles from 0.0 to 3.0% has the same effect, where the two quantities increase by 1.31 and 1.07, respectively, for a triangularly corrugated pipe at a Reynolds number of 1.5×104. The mean temperature gradient contributes most to the thermal entropy production rate, compared to the turbulent temperature gradient. However, the opposite is the case for the viscous entropy production rate. Furthermore, the presence of corrugation was found to increase the viscous entropy production rate but reduce the thermal entropy production rate. The normalized thermal and viscous entropy production rates (referencing a smooth pipe) in circularly, triangularly, and trapezoidally corrugated pipes are {0.81, 0.75}, {0.56,3.38}, and {3.29,3.45}, respectively. It is also noticed that the Bejan number decreases as the Reynolds number increases by 51.4, 81.4, 82.2, and 87.6% for smooth, circularly corrugated, triangularly corrugated, and trapezoidally corrugated pipes, respectively.

Restoring the conservativity of characteristic-based segregated models: Application to the hybrid lattice Boltzmann method

A general methodology is introduced to build conservative numerical models for fluid simulations based on segregated schemes, where mass, momentum, and energy equations are solved by different methods. It is especially designed here for developing new numerical discretizations of the total energy equation and adapted to a thermal coupling with the lattice Boltzmann method (LBM). The proposed methodology is based on a linear equivalence with standard discretizations of the entropy equation, which, as a characteristic variable of the Euler system, allows efficiently decoupling the energy equation with the LBM. To this extent, any LBM scheme is equivalently written under a finite-volume formulation involving fluxes, which are further included in the total energy equation as numerical corrections. The viscous heat production is implicitly considered thanks to the knowledge of the LBM momentum flux. Three models are subsequently derived: a first-order upwind, a Lax–Wendroff, and a third-order Godunov-type schemes. They are assessed on standard academic test cases: a Couette flow, entropy spot and vortex convections, a Sod shock tube, several two-dimensional Riemann problems, and a shock–vortex interaction. Three key features are then exhibited: (1) the models are conservative by construction, recovering correct jump relations across shock waves; (2) the stability and accuracy of entropy modes can be explicitly controlled; and (3) the low dissipation of the LBM for isentropic phenomena is preserved.

Flow Loss Analysis and Optimal Design of a Diving Tubular Pump

As important parts of underground water conveyance equipment, diving tubular pumps are widely used in various fields related to the national economy. Research and development of submersible pumps with better performance have become green goals that need to be achieved urgently in low-carbon development. This paper provides an effective approach for the enhancement of the performance of a diving tubular pump by adopting computational fluid dynamics, one-dimensional theory, and response surface methodology. First, the flow loss characteristics of the pump under several flow rate conditions are analyzed by entropy production theory, and then the impeller and guide vanes are redesigned using the traditional one-dimensional theory. Then, the surface response experimental method is used to improve pump hydraulic efficiency. The streamline angle (A) of the front cover of the impeller blade, the placement angle (B) of the middle streamline inlet, and the placement angle (C) of the rear cover flowline inlet are the response variables to optimize the design parameters of the diving tubular pump. Results show that wall entropy production and turbulent kinetic energy entropy production play the leading role in the internal flow loss of the diving tubular pump, while viscous entropy production can be ignored. The flow loss inside the impeller is mainly concentrated at the inlet and the outlet of the impeller blade, and the flow loss inside the guide vane is mainly concentrated in the area near the guide vane and the entrance of the guide vane. A, B, and C are all significant factors that affect efficiency. The order of the influencing factors from strong to weak is as follows: A2 (p = 0.000) > C (p = 0.007) = A × B (p = 0.007) > B (p = 0.023) > B2 (p = 0.066) > A × C (p = 0.094) > A (p = 0.162) > C2 (p = 0.386) > A × B (p = 0.421). The best combination of response variables after surface response test design is A = 9°, B = 31°, and C = 36°. After optimization, the pump efficiency and the head of the model pump are increased by 32.99% and 18.71%, respectively, under the design flow rate. The optimized model pump is subjected to tests, and the test data and the simulation data are in good agreement, which proves the feasibility of using the surface response method to optimize the design of the model pump.

Entropy production analysis for nanofluid flow through a channel with perforated transverse twisted-baffles

ABSTRACT In the present paper, an entropy production analysis is carried out on the heat transport and nanofluid flow through a 3D channel equipped with perforated transverse twisted-baffles. The finite volume technique is used for the simulation of the heat transport in the system. The Brownian motion of the nanoparticles is included in the simulation. Twisted baffles with three pitch intensities () are mounted inside the duct. The angle of twisted baffles is varied from (vertical) to (horizontal). The number of holes considered in this study is 0, 4, 6, and 8. Alumina/water nanofluid with the nanoparticles concentration of 3% is employed as the fluid. The influences of different parameters, including the angle and pitch of baffles and the number of holes, on the heat transport, pressure loss, and entropy production are studied. The results show that with increasing the number of holes on the baffles, the heat transport coefficient is boosted and the pressure loss in the channel is declined. The minimum pressure loss can be observed for the case of the perforated baffle with eight holes and the pitch of . For this case, the pressure loss decreases by 1.3% and the heat transport coefficient increases about 3.9% as compared to those for the empty channel. The maximum performance evaluation criterion can be achieved as the perforated baffles with four holes and the pitch of are used and it has the value of 1.3 at . As the baffle pitch is boosted from to , the heat transport coefficient is increased slightly. This increase is 2.5% at . The viscous entropy production declines as the holes are created on the baffles. By moving along the channel length, the thermal irreversibility is extended toward the center of the channel owing to thickening the thermal boundary layer.

Thermal-Fluid-Solid Coupling-Parametrical Numerical Analysis of Hot Turbine Nozzle Guide Vane.

The cooling technology of hot turbine components has been a subject of continuous improvement for decades. In high-pressure turbine blades, the regions most affected by the excessive corrosion are the leading and trailing edges. In addition, high Kt regions at the hot gas path are exposed to cracking due to the low and high cycle fatigue failure modes. Especially in the case of a nozzle guide vane, the ability to predict thermally driven loads is crucial to assess its life and robustness. The difficulties in measuring thermal properties in hot conditions considerably limit the number of experimental results available in the literature. One of the most popular test cases is a NASA C3X vane, but coolant temperature is not explicitly revealed in the test report. As a result of that, numerous scientific works validated against that vane are potentially inconsistent. To address that ambiguity, the presented work was performed on a fully structural and a very fine mesh assuming room inlet temperature on every cooling channel. Special attention was paid to the options of the SST (shear-stress transport) viscosity model, such as Viscous heating (VH), Curvature correction (CC), Production Kato-Launder (KT), and Production limiter (PL). The strongest impact was from the Viscous heating, as it increases local vane temperature by as much as 40 deg. The significance of turbulent Prandtl number impact was also investigated. The default option used in the commercial CFD code is set to 0.85. Presented study modifies that value using equations proposed by Wassel/Catton and Kays/Crawford. Additionally, the comparison between four, two, and one-equation viscosity models was performed.

Predictions of Conjugate Heat Transfer in Turbulent Channel Flow Using Advanced Wall-Modeled Large Eddy Simulation Techniques.

In this paper, advanced wall-modeled large eddy simulation (LES) techniques are used to predict conjugate heat transfer processes in turbulent channel flow. Thereby, the thermal energy transfer process involves an interaction of conduction within a solid body and convection from the solid surface by fluid motion. The approaches comprise a two-layer RANS–LES approach (zonal LES), a hybrid RANS–LES representative, the so-called improved delayed detached eddy simulation method (IDDES) and a non-equilibrium wall function model (WFLES), respectively. The results obtained are evaluated in comparison with direct numerical simulation (DNS) data and wall-resolved LES including thermal cases of large Reynolds numbers where DNS data are not available in the literature. It turns out that zonal LES, IDDES and WFLES are able to predict heat and fluid flow statistics along with wall shear stresses and Nusselt numbers accurately and that are physically consistent. Furthermore, it is found that IDDES, WFLES and zonal LES exhibit significantly lower computational costs than wall-resolved LES. Since IDDES and especially zonal LES require considerable extra work to generate numerical grids, this study indicates in particular that WFLES offers a promising near-wall modeling strategy for LES of conjugated heat transfer problems. Finally, an entropy generation analysis using the various models showed that the viscous entropy production is zero inside the solid region, peaks at the solid–fluid interface and decreases rapidly with increasing wall distance within the fluid region. Except inside the solid region, where steep temperature gradients lead to high (thermal) entropy generation rates, a similar behavior is monitored for the entropy generation by heat transfer process.

Numerical modeling of entropy production in Al2O3/H2O nanofluid flowing through a novel Bessel-like converging pipe

Optimization of thermal systems requires higher heat transfer rate and lower entropy production rate. The review of literature shows that there are limited works on entropy production rate of nanofluids flowing through a converging pipe as the available ones only considered entropy production rate in a linear converging pipe. In this study, a 2D-computational fluid dynamic model is set up to investigate entropy production rate of Al2O3 nanofluid flowing through novel Bessel-like convergent pipes in laminar flow regime. The effect of Reynolds number $$\left( {300 \le {\text{Re}} \le 1200} \right)$$ , nanoparticle concentration $$\left( {0 \le \varphi \le 0.1} \right)$$ , and convergent index $$\left( {n = 0 - 3} \right)$$ on the entropy production rate, heat transfer effectiveness number, and irreversibility distribution ratio were considered. The results obtained revealed that increase in convergent index enhances viscous entropy production rate, but diminishes thermal entropy production rate. For instance, the reduction in thermal entropy production rate at $${\text{Re}} = 900$$ between pipe corresponds to $$n = 0$$ and $$n = 3$$ was 51.98% while the increase in viscous entropy production rate was 753.65%. Furthermore, a new correlation was developed using response surface methodology to estimate the entropy production rate as a function of the Reynolds number, nanoparticle concentration, and convergence index. The overall result shows that the usage of converging pipe in place of straight pipe is more advantageous.

Improving the Efficiency and Transportation of High- Viscosity Oils by Emulsification and Creating a Coaxial Flow

Currently, high-viscosity oil fields are actively developed in the world. This is due to the depletion of world reserves of light oils and a significant resource of heavy high-viscosity oils. The viscous oil production requires a solution to the issue of its transportation, which becomes much more complicated. This is determined by greatly increasing pressure loss due to hydraulic resistance when pumping heavy oil. To reduce the loss of the head, the pumped oil viscosity should be decreased. The paper considers improving the efficiency and transportation of high-viscosity oil by emulsification and creating a coaxial flow.

Improved compressible hybrid lattice Boltzmann method on standard lattice for subsonic and supersonic flows

A D2Q9 Hybrid Lattice Boltzmann Method (HLBM) is proposed for the simulation of both compressible subsonic and supersonic flows. This HLBM is an extension of the model of Feng et al. [1], which has been found, via different test cases, to be unstable for supersonic regimes. To circumvent this limitation, we propose:: (1) a new discretization of the lattice closure correction term that makes possible the simulation of supersonic flows, (2) a corrected viscous stress tensor that takes into account polyatomic gases, and (3) a novel discretization of the viscous heat production term fitting with the regularized formalism. The result is a hybrid method that resolves the mass and momentum equations with an LBM algorithm, and resolves the entropy-based energy equation with a finite volume method. This approach fully recovers the physics of the Navier–Stokes–Fourier equations with the ideal gas equation of state, and is valid from subsonic to supersonic regimes. It is then successfully assessed with both smooth flows and flows involving shocks. The proposed model is shown to be an efficient, accurate, and robust alternative to classic Navier–Stokes methods for the simulation of compressible flows.