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The purpose of this study is to evaluate the methods employed for classifying and quantifying the potential of squeezing in tunnels. Along with the empirical and semi‐empirical approaches presently available in order to anticipate the potential of squeezing tunnel problems, the squeezing potential of Karaj water transfer tunnel and North West Tunnel Convey (NWTC) tunnels (Lot 2), located in Iran, are evaluated and presented. Those two case studies have an interesting geology profile and parameters to identify and then evaluate the squeezing potential.

In recent years, there has been an increasing interest in the tunnel construction. This paper describes the squeezing behavior of poor rock mass associated with deformability and strength properties. In Karaj water transfer tunnel, there are eight lithological rock types; and NWTC tunnel (Lot2) has 21 Lithological rock types. The parameters for rock classification, such as rock quality designation (RQD), rock mass rating (RMR), modified RMR, Q‐system, geological strength index (GSI), rock mass index (RMi), and rock structure rating (RSR) are evaluated and presented here. The parameters mentioned above are the input parameters for squeezing study in Karaj and NWTC tunnels. According to different methods of squeezing evaluation of tunnel presented in tables, the results of two case studies are presented in this paper.

One of the more significant findings to emerge from this study showed that about 3 km of the second part of NWTC tunnel, and 2 km of the Karaj tunnel have high squeezing potential. This research deals with not only an overview of the methods used for the identifying and quantifying of squeezing along with the empirical and semi‐empirical approaches presently available in order to anticipate the potential of squeezing tunnel problem, but also the case studies of NWTC and Karaj tunnels to evaluate and compare the potential of squeezing by different methods. These two tunnel case studies have high potential of squeezing therefore the lining of those two tunnels must be strong enough to overcome this issue.

This study is a precise and concise comparison of the evaluation of tunnels under squeezing rock condition. The present study confirms the previous findings and contributes additional evidence that suggests that there are many studies conducted using empirical and analytical methods to determine the squeezing phenomenon in tunnels. This paper responds to the various questions like, what is the squeezing phenomenon. How can we quantify the potential of squeezing in weak rock? What are the different approaches to the understanding of squeezing phenomenon?

The influences of viscous shear stresses on the squeezing film behaviors in porous journal bearings with infinite length are analyzed. Based on the Brinkman model, two general coupled Reynolds‐type equations derived between two curved surfaces are applied to evaluate the bearing characteristics. According to the results obtained, the Brinkman model predicts quite different squeezing film performances to those obtained by using the slip‐flow model and the Darcy model. In addition, the quantitative effects of viscous shear stresses of the Brinkman model upon the porous squeezing film characteristics are more pronounced for porous journal bearings with moderate permeability parameters and higher eccentricity ratios.

Casing damage problems are increasingly prominent in oil fields, most of which were caused by casing external squeezing loads. The traditional calculation method of casing external squeezing loads is not very accurate now, especially in complex formation. The purpose of this paper is to propose a new calculation method to solve the problem of actual casing loads under above conditions.

Based on Lame’s model of elastic mechanics, a new calculation method of casing external squeezing loads is deduced. Comprehensive influence laws of the loads which caused by in-situ stress, internal pressure, formation parameters, cement annulus parameters and casing parameters are analyzed.

The paper provides a new calculation method of casing external squeezing loads, by which the dispersion effect of internal liquid pressure caused by casing wall material is eliminated. The main influence factors of casing external squeezing loads are in-situ stress and formation elastic modulus.

The model and boundary conditions used in the paper is based on elastic mechanics. The accuracy of the calculation results depends on the quality and accuracy of the input formation parameters.

This paper proposes a new method to calculate casing external squeezing loads. And compared with traditional methods, this method is more practical.

This paper aims to investigate the squeeze film lubrication properties of hexagonal patterned surface inspired by the epidermis structure of tree frog’s toe pad and numerically explore the working mechanism of hexagonal micropillar during the acquisition process of high adhesive and friction for wet contacts.

A two-dimensional elastohydrodynamic numerical model is employed for the squeezing contacts. The pressure distribution, load carrying capacity and liquid flow rate of the squeeze film are obtained through a simultaneous solution of the two-dimensional Reynolds equation and elasticity deformation equations.

Higher pressure is found to be longitudinally distributed across individual hexagonal pillar, with pressure peak emerging at the center of hexagonal pillar. Expanding the area density and shrinking the channel depth or initial film thickness will improve the magnitude of squeezing pressure. Relatively lower pressure is generated inside interconnected channels, which reduces the load carrying capacity of the squeeze film. Meanwhile, the introduction of microchannel is revealed to downscale the total mass flow rate of squeezing contacts.

This paper provides a good proof for the working mechanism of surface microstructures during the acquisition process of high adhesive and friction for wet contacts.

This study aims to explore the idea of solving the problem of squeezing nanofluid flow between two parallel plates using a novel mathematical method.

The unsteady squeezing flow is a coupled fourth-order boundary value problem with flow velocity and temperature as the desired unknowns. In the first step, the conditions that guarantee the existence of a unique solution are obtained. Then following Green’s function-based approach, an iterative method for solving the problem is developed.

The accuracy of the method is examined by comparing the obtained results with existing numerical data, indicating excellent agreement between the two. In addition, the effects of nanoparticle shape and volume fraction on the flow and heat transfer characteristics are addressed. The results reveal that although the nanoparticle shape strongly affects the temperature distribution in the squeezing flow, it only has a slight impact on the velocity field. Furthermore, the highest and lowest Nusselt numbers belong to the platelets and spherical nanoparticles, respectively.

A semi-analytical method with computational support is developed for solving the unsteady squeezing flow problem. Moreover, the existence and uniqueness of the solution are discussed for the first time.

The purpose of this paper is to numerically solve the problem of an unsteady squeezing three-dimensional flow and heat transfer of a nanofluid in rotating vertical channel of stretching left plane. The fluid is assumed to be Newtonian, incompressible and electrically conducting embedded with nanoparticles. Effect of internal heat generation/ absorption is also considered in energy equation. Four different types of nanoparticles are considered, namely, copper (Cu), alumina (Al₂O₃), silver (Ag) and titanium oxide (TiO₂) with the base fluid as water. Maxwell-Garnetts and Brinkman models are, respectively, employed to calculate the effective thermal conductivity and viscosity of the nanofluid.

Using suitable similarity transformations, the governing partial differential equations are transformed into set of ordinary differential equations. Resultant equations have been solved numerically using Runge-Kutta-Fehlberg fourth fifth order method for different values of the governing parameters. Effects of pertinent parameters on normal, axial and tangential components of velocity and temperature distributions are presented through graphs and discussed in detail. Further, effects of nanoparticle volume fraction, squeezing parameter, suction/injection parameter and heat source/sink parameter on skin friction and local Nusselt number profiles for different nanoparticles are presented in tables and analyzed.

Squeezing effect enhances the temperature field and consequently reduces the heat transfer rate. Large values of mixed convection parameter showed a significant effect on velocity components. Also, in many heat transfer applications, nanofluids are potentially useful because of their novel properties. They exhibit high-thermal conductivity compared to the base fluids. Further, squeezing and rotation effects are desirable in control the heat transfer.

Three-dimensional mixed convection flows over in rotating vertical channel filled with nanofluid are very rare in the literature. Mixed convection squeezing three-dimensional flow in a rotating channel filled with nanofluid is first time investigated.

Inspired by the high-friction performance of the soft toe pads of tree frogs, this study aims to investigate the effect of elastic deformation on the lubrication properties of squeezing films inside soft tribocontacts with microstructured surface under wet conditions.

A one-dimensional hydrodynamic extrusion model was used to study the film lubrication characteristics of conformal contact. The lubrication characteristics of the extruded film, including load-carrying capacity, liquid flow and surface elastic deformation, were obtained through the simultaneously iterative solution of the fluid-governing and deformation equations.

The results show that the hydrodynamic pressure is approximating parabolically and symmetrically distributed in the contact area, and the peak value appears in the center of the extrusion surface. Elastic deformation increases the thickness of the liquid film, weakens the bearing capacity and homogenizes the liquid flow rate of inside soft friction contact. The magnitude of this effect greatly increases as the initial liquid film thickness decreases. Moreover, the elastic deformation directly affects the average film thickness of the extrusion contact. Narrow and shallow microchannels are found to result in a more prominent elastic deformation on the microstructured soft surface.

These results present a design for soft tribocontacts suitable for submerged or wet environments involving high friction, such as wiper blades, in situ flexible electrons and underwater robots.

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-02-2024-0049/

The paper aims to investigate the effect of the electromagnetic field on the convective events which occur when electrically conducting fluid is squeezed between two parallel disks.

The effects of the current occurring due to the direct voltage power supply at the thin electrical conducting fluid layer squeezed between the parallel disks, the magnetic field inducted by this current, and Ohmic heating on the squeezing process and heat convection are considered. Both approximate analytical and numerical solutions of the problem are obtained and a good agreement is observed between them.

The effects of the basic parameters such as Hartmann number, Reynolds number, the ratio of the distance between the disks to the radius of the disks, Prandtl number, Eckert number, heat conduction, and electric current on the squeezing event, and load capacity of the fluid between two parallel disks are able to be determined from the solutions. These solutions also enable the effects of the basic parameters such as Hartmann number, Reynolds number, the ratio of the distance between the disks to the radius of the disks, Prandtl number, Eckert number, heat conduction, and electric current on the squeezing event and load capacity of the fluid between two parallel disks to be determined.

Some important results and comparisons are presented graphically.

The purpose of this paper is to find the approximate solutions of unsteady squeezing nanofluid flow and heat transfer between two parallel plates in the presence of variable heat source, viscous dissipation and inclined magnetic field using collocation method (CM).

The partial governing equations are reduced to nonlinear ordinary differential equations by using appropriate transformations and then are solved analytically by using the CM.

It is observed that the enhancing values of aligned angle of the magnetic causes a reduction in temperature distribution. It is also seen that the effect of nanoparticle volume fraction is significant on the temperature but negligible on the velocity profile.

To the best of the authors’ knowledge, no research has been carried out considering the combined effects of inclined Lorentz forces and variable heat source on squeezing flow and heat transfer of nanofluid between the infinite parallel plates.

The purpose of this paper is to construct mathematical model for squeezed flow of carbon-water nanofluid between parallel disks considering Darcy–Forchheimer porous medium. Thermal conductivity of carbon nanotubes is estimated through the well-known Xue model. Such research work is not carried out in the past even in the absence of Darcy–Forchheimer porous space. Forchheimer equation is preferred here to account for both low and high velocity inertial effects. Researchers also found that dispersion of carbon nanotubes in water elevates the thermal conductivity of resulting nanofluid by 100 per cent.

Homotopy analysis method (HAM) is used for the convergent series solutions of the governing system.

Nusselt number at the lower disk increases when squeezing parameter Sq enlarges. This illustrates that heat transfer rate at the lower wall can be enhanced by increasing the squeezing velocity of the lower disk. The results demonstrate a decreasing trend in temperature profile for increasing volume fraction of carbon nanotubes. Moreover, improvement in heat transfer rate because of existence of carbon nanotubes is also apparent. A significant enhancement in temperature profile is depicted when inertial permeability coefficient is enhanced. Skin friction coefficients at the lower and upper disks are higher for MWCNTs in comparison to the SWCNTs.

To the best of author’s knowledge, no such consideration has been given in the literature yet.