AI multi-parameters Bayesian with Genetic optimization for the Hall effect on squeezing slip flow

Forced convection of slip flow at the entrance region in rhombic microchannels

Laminar forced convective slip flow in a microchannel with piecewise constant temperature in axial direction

Underwater drag and icing pose significant challenges in navigation bodies such as ship navigation. Despite the importance of mitigating these challenges, functional surfaces that can integrate both anti-icing and drag-reduction properties remain scarce. In this work, we fabricate a superhydrophobic coating by spraying modified TiO2 nanoparticles on Al substrates, which can reduce drag while delaying icing. The superhydrophobic coating demonstrated excellent drag reduction performance, with a drag reduction rate of 39.8%. At the same time, under a low-temperature environment of 15 °C, the superhydrophobic coating delayed the ice formation rate by 6 times compared to the substrate. This is because the rough micronano structure of the superhydrophobic coating can trap air. The trapped air not only generates gas-liquid interfaces that replace solid-liquid interfaces, inducing slip flow and thereby reducing drag, but also reduces the thermal exchange between the droplets and the substrate and delays the nucleation of ice, thereby achieving delayed freezing. Therefore, this study proposes a novel method for large-area preparation of functional surfaces with drag reduction capabilities and provides an anti-icing capability.

ABSTRACT Engineers face a major challenge when understanding how internal molecular interactions, such as shapes and aggregation kinetics, affect the fluid’s thermal physical properties. As a result, figuring out the ideal particle’s thermal effect at the nanoscale depends critically on the aggregation kinematics of nanoparticles. Thus, this investigation aims to study the characteristics of the aggregated nanoparticles and how they influence the slip flow of a power-law nanofluid towards a thin needle. Further, the effects of the heat source/sink are taken into account. After converting the governing equations to a nondimensional version with appropriate transformation, the BVP4c approach is implemented to solve it. The outcomes reveal that the velocity profile diminished for higher values of Ag -volume fraction, power-law index, and thermal slip parameter. Velocity and thermal slip effects reduced the temperature distribution. Additionally, regression analysis is performed to establish a deeper understanding of engineering quantities. The heat transmission rate in the aggregating nanoparticle improved relative to the non-aggregating nanoparticle as the Ag volume fraction and velocity slip parameters were enhanced. Aggregated nanoparticles maximize cooling efficiency, enhancing electronic devices’ reliability and lifespan and improving performance.

Slip flow and shadowing effects in multilayered fibrous filter media

Unsteady MHD Oscillatory Slip Flow of Casson Fluid with Heat Source/Sink Through a Porous Medium

New experimental results on gas flow through a long tube in the viscous, slip and transitional regimes are presented, obtained using an improved constant-volume measurement technique. This method is based on measuring the pressure variation in the inlet tank while the outlet tank is evacuated to a low pressure. Experimental pressure data for helium, neon, argon, nitrogen, krypton and xenon are used to extract the Poiseuille coefficient through a newly developed methodology. The obtained values show good agreement with theoretical predictions. Additionally, the velocity slip coefficient is also extracted from the same pressure data for all tested gases.

Hydrodynamic electron transport in solids, governed by momentum-conserving electron-electron collisions, offers a unique framework to explore collective phenomena. Within this framework, correlated electron motion is modeled as viscous fluid flow, with viscosity serving as the interaction parameter. Advances in electron hydrodynamics remain constrained by two unresolved issues: the questionable existence of materials with intrinsically smooth boundaries enabling perfect slip in electron fluids and the lack of quantitative experimental confirmation of the theoretical relation linking the viscosity to electron-electron scattering length. Here, we resolve this through measurements of these quantities in the same electron system in GaAs/AlGaAs heterostructure. Our experiments reveal large flow slippage at boundaries of microscale constrictions-an unexpected phenomenon for electron liquid that parallels ultrafast water transport in carbon nanotubes. These findings bridge the fields of electron hydrodynamics and nanofluidics, highlighting the transformative potential of hydrodynamic engineering across condensed matter and fluidic technologies.

Thermal energy optimization in Darcy-Forchheimer slip flow featuring viscoplastic (Casson) model subjected to diffusion of chemically reactive species

ABSTRACT The star fruit ( Averrhoa carambola ) samples are collected randomly from the market of Rangiya, a major city of the Lower Assam division in the Kamrup region of Assam, India. The rheometer ARES‐G2 is used to collect experimental data on the juice's rheological flow characteristics at different temperatures. The curve tracing tool is then used to fit the data to the Power‐law fluid model. A mathematical analysis is conducted to interpret the influence of slip on the flow and heat transfer of star fruit juice past a moving permeable sheet. The resulting governing equations, along with relevant boundary conditions, are obtained utilizing appropriate similarity variables. The MATLAB programming code “bvp4c” is employed to compute the governing equations. With the aid of relevant flow parameters, the momentum and thermal profiles are plotted for discussion. Using graphical analysis, the impacts of the slip parameter, flow index, Eckert number, and heat generation or absorption parameter are investigated, and conclusions are made based on physical insights. To examine the impacts of the relevant flow parameters, the Nusselt number and local skin friction values are also tabulated. The study examines how rheological parameters influence the flow characteristics, which is helpful in designing and evaluating juice transportation systems.

ABSTRACT In natural circulation loops (NC loops), flow initiation is driven by the difference between the heat source and the heat sink density variations. Given that the flow rates within these loops are lower than those in forced convection channels, surface characteristics can significantly influence the flow. No heat transfer studies have been found that describe the effects of UV‐irradiated PDMS surface modifications in NC loops. The study focuses on evaluating the thermal performance of surface‐modified natural circulation mini‐loops with a hydraulic diameter of 3 mm. The impact of surface modifications at the mini‐loop heater section, under different power inputs (10, 15, and 20 W) and temperatures at the heat sink (20°C and 30°C), is investigated. The performance of 0.01 and 0.02 vol.% Al 2 O 3 and SiO 2 nanofluids was measured and compared with that of D.I. water. The initial experiment involved a channel with untreated polydimethylsiloxane (PDMS) coating on the heater section (contact angle of 86.2 ± 2.7°). Subsequently, the experiment was repeated with a vacuum UV (VUV)‐treated PDMS coating (contact angle of 2.7 ± 2.1°). The heat transfer coefficient within the heater section was estimated using a nonintrusive interferometric technique. The thermal performance of a 3 mm hydraulic diameter mini‐loop with dilute metal oxide nanofluids was compared with deionized water (D.I. water), and the results were validated against Vijayan's correlation. Figure of Merit (FOM) analysis indicated that, for the designed mini‐loop, 0.02 vol.% alumina nanofluid exhibited the best performance. At 10 W and 283 K, the surface‐tuned heater section with 0.02 vol.% alumina nanofluid demonstrated a 12.42 ± 1.6% enhancement in the local heat transfer coefficient. However, the Nusselt number increment was only 5.39 ± 1.7%. The high wettability of the heater section hinders the slip flow. The rise in the thermal conductivity of the basefluid due to nanoparticle addition also reduces the Nusselt number. The surface effects being comparable with the buoyancy forces, the Reynolds number inside the loop is lower.

A gas-liquid slip flow model for predicting bubble distribution and electrolyte blockage in porous electrodes of flow batteries

Correction: Numerical analysis of chemically reactive MHD slip flow of nanofluids over an elongated cylinder: effects of entropy generation, heat flux and double stratification

Hydrodynamics provides a continuum-level description of fluid motion, but its applicability at the nanoscale becomes uncertain due to the emerging importance of molecular-level effects such as spatial heterogeneity. Hydrodynamic boundary conditions that incorporate molecular details allow us to partition the system into a near-wall region and a bulk fluid region. We identify a hydrodynamic wall located inside the fluid that determines where slip begins. By extending the hydrodynamic wall with the slip length, the position of the extrapolated wall is established. This offers a unified description of both slip and stagnant flow behaviors, with wall hydrophobicity characterized by the relative location of the extrapolated wall with respect to the physical wall. Employing this concept in analyses of equilibrium molecular dynamics (MD) and non-equilibrium MD simulations of Couette and Poiseuille flows, our results demonstrate consistency between equilibrium and non-equilibrium approaches across different flow types and confinement levels. This demonstrates the robust nature of linear response theory. We then explore the effects of fluid-wall and bulk fluid interactions on the hydrodynamic properties. These findings enhance the effectiveness of molecular-based simulations for investigating complex confined systems in nanofluidics, biology, and colloidal science, offering a complementary molecular-scale perspective to traditional continuum approaches.

Exponential space source characteristics on non-Newtonian slip flow and radiated heat transfer through a curved surface

This study investigates the unsteady fluctuations of a conducting Newtonian viscous fluid in a rotating frame influenced by an unsteady hydromagnetic free-stream flow, while also accounting for chemical reactions and heat absorption. The flow regime is modeled using partial differential equations. In contrast to previous research, this study employs a fractionalized dimensionless system of equations based on the newly developed Caputo–Fabrizio derivative. The dimensionless profiles for velocity, temperature, and concentration are solved accurately using the Laplace transform. The effects of various parameters are illustrated graphically and discussed in detail. Additionally, their influences are summarized in a table. Key observations reveal that as Hall current increases, primary velocity decreases when near the plate, but subsequently increases as the fluid moves away. Furthermore, skin friction shows a notable increase with rotation. Buoyancy forces not only enhance skin friction but also grow over time, while heat absorption leads to a reduction in fluid temperature.

This study discusses hydromagnetic flow and the movement of a fluid with adhesive property through a channel that is semi-porous. For this purpose, the slip condition is taken at a bottom wall and its thermal effects are noted. Presumably, the channel has porous upper boundaries and non-porous lower boundaries. The equation of fluid motion and a number of linear ordinary differential equations are combined. To find a simplified logical equation, Homotopy Analysis Method (HAM) is applied. For numerical computations of the problem, the shooting method is applied. The heat transfer effects in the flow, being complex, are simplified into graphic displays. Both methods are equally compared, as shown through graphs.

Numerical analysis of chemically reactive MHD slip flow of nanofluids over an elongated cylinder: effects of entropy generation, heat flux and double stratification

The ability of the applied chemical concentration gradients to move the fluid, i.e., diffusioosmosis, requires a more robust mathematical model to predict the interdependency of the solute dispersion and the fluid movement. The present work illustrates the influence of applied concentration gradient on the movement of micropolar fluid within the microchannel using the mathematical model of diffusioosmosis. The model consists of a rectangular channel filled with micropolar fluid in which the solute concentration gradient is imposed, having a standard Gaussian distribution. The model for combined advection-diffusion, i.e., Taylor's dispersion model, is employed to regulate the solute distribution. The diffusioosmotic pressure gradient purely drives the micropolar fluid through the diffusioosmotic slip flow at the wall. A multi-timescale approach is utilized to obtain the closed-form solution of the flow and concentration profiles. The combined approach of homogenization and the Laplace transformation is used to find the analytical expressions of the concentration profile. The pure diffusion and the solute wall interaction induce the slip flow at the wall, which further contributes to solute dispersion by advection, leading to the combined advection-diffusion process. The two different boundary constraints for microrotation at the wall, including no-spin (NS) and no-couple stress (NCS), have been thoroughly studied. The graphical illustrations of the various dynamic quantities provide a comprehensive analysis of their physical behavior under the influence of relevant flow parameters. It is noted that for stronger diffusioosmosis, all the dynamic quantities, including the velocity profile, rotational velocity, effective diffusivity, wall shear stress (WSS), and mean concentration, are sensitive to micropolar fluid parameters like micro-scale parameter and coupling number. It is observed that the velocity profile and mean concentration show less variation concerning different parameters for no-couple stress at the wall, compared to the no spin of the microparticles at the wall. Further, the outcomes from the mathematical model advance the understanding of fluid flow induced by concentration gradients, which can assist the researchers in analyzing drug delivery, the separation process, and various species transport applications in the novel framework of diffusioosmosis.