Basal stress controls ice-flow variability during a surge cycle of Hagen Bræ, Greenland

Basal conditions play an essential role in the dynamics of outlet glaciers, but direct observations at the bed of glaciers are challenging to obtain. Instead, inverse methods can be used to infer basal parameters from surface observations. Here, we use a simple ice-flow model as a forward model in an inversion scheme to retrieve the spatio-temporally variable basal stress parameter for Hagen Bræ, North Greenland, from 1990 to 2020. Hagen Bræ is a surge-type glacier with up to an order of magnitude variability of winter velocities near the grounding line. We find that downstream changes in the basal stress parameter can explain most of the variation of flow velocity, and we further identify a region of high resistance ~20–40 km from the grounding line. We hypothesise that this region of high resistance plays an important role in controlling glacier discharge.

Effects of axial motion and couple stress on lubrication performances of ship stern shaft

Increasingly prominent marine oil pollution problems highlight the importance of environmentally friendly lubricants in a ship. According to the actual navigation environment, the couple stress effect of environmentally friendly lubricants and axial motion of stern shaft is considered to establish a new hydrodynamic lubrication model, and finite difference method and Simpson integral method have been utilized to solve film pressure and bearing carrying capacity, respectively. Various performance characteristics were obtained for a range of couple stress parameters, misalignment angles and rotation speeds. The results show that axial motion and couple stress have opposite effects on film distribution, the minimum film thickness decreases with the increasing of axial velocity while the maximum film pressure significant reduce as couple stress parameter grows. The axial position corresponding to the maximum pressure is reduced from 0.51 to 0.49 m as axial velocity enhances from 0 to 0.8 m/s while couple stress parameter is 0, but nearly remains the place while couple stress is considered. Meanwhile, couple stress lubricants effectively restrain friction of journal caused by hydrodynamic effect, and the decreasing amplitude is nearly independent of axial velocity.

Study of Slip Effects in Reverse Roll Coating Process Using Non-Isothermal Couple Stress Fluid

The non-isothermal couple stress fluid inside a reverse roll coating geometry is considered. The slip condition is considered at the surfaces of the rolls. To develop the flow equations, the mathematical modelling is performed using conservation of momentum, mass, and energy. The LAT (lubrication approximation theory) is employed to simplify the equations. The closed form solution for velocity, temperature, and pressure gradient is obtained. While the pressure and flow rate are obtained numerically. The impact of involved parameters on important physical quantities such as temperature, pressure, and pressure gradient are elaborated through graphs and in tabular form. The pressure and pressure gradient decreases for variation of the couple stress parameter and velocity ratio parameter K. While the variation of the slip parameter increases the pressure and pressure gradient inside the flow geometry. Additionally, flow rate decreases for the variation of the slip parameter as fluid starts moving rapidly along the roller surface. The most important physical quantity which is responsible for maintaining the quality of the coating and thickness is flow rate. For variation of both the couple stress parameter and the slip parameter, the flow rate decreases compared to the Newtonian case, consequently the coating thickness decreases for the variation of the discussed parameter.

Time Fractional Analysis of Channel Flow of Couple Stress Casson Fluid using Fick’s and Fourier’s Laws

This study aim to examine the channel flow of a couple stress Casson fluid. The flow is generated due to the motion of the plate at y = o, while the plate at y = d is at rest. This physical phenomenon is derived in terms of partial differential equations. The subjected governing PDE’s are non-dimensionalized with the help of dimensionless variables. The dimensionless classical model is generalized by transforming it to the time fractional model using Fick’s and Fourier’s Laws. The general fractional model is solved by applying the Laplace and Fourier integral transformation. Furthermore, the parametric influence of various physical parameters like Casson parameter, couple stress parameter, Grashof number, Schmidt number and Prandtl number on velocity, temperature, and concentration distributions is shown graphically and discussed. The heat transfer rate, skin friction, and Sherwood number are calculated and presented in tabular form. It is worth noting that the increasing values of the couple stress parameter λ deaccelerate the velocity of Couple stress Casson fluid.