Constraining tectonic uplift and advection from the main drainage divide of a mountain belt

One of the most conspicuous features of a mountain belt is the main drainage divide. Divide location is influenced by a number of parameters, including tectonic uplift and horizontal advection. Thus, the topography of mountain belts can be used as an archive to extract tectonic information. Here we combine numerical landscape evolution modelling and analytical solutions to demonstrate that mountain asymmetry, determined by the location of the main drainage divide, increases with increasing uplift gradient and advection velocity. Then, we provide a conceptual framework to constrain the present or previous tectonic uplift and advection of a mountain belt from the location and migration direction of its main drainage divide. Furthermore, we apply our model to Wula Shan horst, Northeastern Sicily, and Southern Taiwan.

Study on the Coupled Heat Transfer Model Based on Groundwater Advection and Axial Heat Conduction for the Double U-Tube Vertical Borehole Heat Exchanger

In this paper, a dynamic heat transfer model for the vertical double U-tube borehole heat exchanger (BHE) was developed to comprehensively address the coupled heat transfer between the in-tube fluid and the soil with groundwater advection. A new concept of the heat transfer effectiveness was also proposed to evaluate the BHE heat exchange performance together with the index of the heat transfer rate. The moving finite line heat source model was selected for heat transfer outside the borehole and the steady-state model for inside the borehole. The data obtained in an on-site thermal response test were used to validate the physical model of the BHE. Then, the effects of soil type, groundwater advection velocity, inlet water flow rate, and temperature on the outlet water temperature of BHE were explored. Results show that ignoring the effects of groundwater advection in sand gravel may lead to deviation in the heat transfer rate of up to 38.9% of the ground loop design. The groundwater advection fosters the heat transfer of BHE. An increase in advection velocity may also help to shorten the time which takes the surrounding soil to reach a stable temperature. The mass flow rate of the inlet water to the BHE should be more than 0.5 kg·s−1 but should not exceed a certain upper limit under the practical engineering applications with common scale BHE. The efficiency of the heat transfer of the double U-tube BHE was determined jointly by factors such as the soil’s physical properties and the groundwater advection velocity.

Similarity of the Output Characteristics of the Small Vertical Axis Wind Turbine

Several models have been proposed to predict the shaft output characteristics of the vertical axis wind turbine from the aerodynamic characteristics of the blade. However, it has not predicted the output characteristics of the small wind turbine, turbine diameter less than 1 m, even the multiple stream tube model included effect of the momentum reduction. A solidity of the small wind turbine become higher than large, i.e. blades interval of small wind turbine becomes short. Therefore, it expects that the wake of preceding blade influence strongly aerodynamic character of following blade. Thus, we have investigated the relation between wake of rotating turbine and its shaft output characteristics. From result obtain, we had cleared the shaft output character agree with variation of momentum loss of the wake of turbine. Moreover, the relevance between the shaft output characteristics and velocity fluctuation in the wake had been found. In the low tip speed ratio region increasing the shaft output, the periodical component synchronized with motion of the blade remarkably appear in velocity fluctuation, and it disappear near the peak of shaft output. Meanwhile, in the high tip speed ratio region decreasing the shaft output, the turbulent component is dominant in velocity fluctuation. It indicates that the blade-wake interference was affected on shaft output of the small wind turbine. Therefore, the purpose of this study was to find out a similarity parameter of the shaft output characteristics based on blade-wake interference. The larger the scale of blade wake or slower the advection velocity of it, the higher the possibility that blade wake generated from previous blade interfere to following blade become. For blade-wake interaction, these two parameters which the scale and the advection velocity of blade wake, are important. Thus, I estimated these parameter in this study using the wind turbine model with single blade. From measurement of the blade wake, I found that the scale of the blade wake depends on the ratio of the rotational speed of the turbine to the free stream velocity, and the advection velocity of blade wake depends on the free stream velocity. From these characteristics of blade wake, I suggest a new parameter based on the blade-wake interaction using tip speed ratio, solidity, number of blade, and turbine diameter. The shaft output characteristics of the small wind turbine indicates good similarity for the new parameter.

Numerical solutions of a 2D fluid problem coupled to a nonlinear non-local reaction-advection-diffusion problem for cell crawling migration in a discoidal domain

In this work, we present a numerical scheme for the approximate solutions of a 2D crawling cell migration problem. The model, defined on a non-deformable discoidal domain, consists in a Darcy fluid problem coupled with a Poisson problem and a reaction-advection-diffusion problem. Moreover, the advection velocity depends on boundary values, making the problem nonlinear and non local. For a discoidal domain, numerical solutions can be obtained using the finite volume method on the polar formulation of the model. Simulations show that different migration behaviours can be captured.

Statistical analysis of Lagrangian transport of subtropical waters in the Japan Sea based on AVISO altimetry data

Northward near-surface Lagrangian transport of subtropical waters in the Japan Sea frontal zone is simulated and analysed based on altimeter data for the period from 2 January 1993 to 15 June 2015. Computing different Lagrangian indicators for a large number of synthetic tracers launched weekly for 21 years in the southern part of the Sea, we find preferred transport pathways across the Subpolar Front. This cross-frontal transport is statistically shown to be meridionally inhomogeneous with gates and barriers whose locations are determined by the local advection velocity field. The gates open due to suitable dispositions of mesoscale eddies facilitating propagation of subtropical waters to the north. It is documented for the western, central and eastern gates with the help of different kinds of Lagrangian maps and verified by some tracks of available drifters. The transport through the gates occurs by a portion-like manner, i.e. subtropical tracers pass the gates in specific places and during specific time intervals. There are some forbidden zones in the frontal area where the northward transport has not been observed during all the observation period. They exist due to long-term peculiarities of the advection velocity field.