A three-dimensional direct numerical simulation was conducted to investigate the vortex–wing interactions through two NACA 0012 stationary wings placed in tandem at a low Reynolds number [ ]. The aerodynamic characteristics and three-dimensional flow structures were analyzed for the tandem wings. The back wing disturbed by the upstream vortices gained an evident increase in aerodynamic performance, where the advantage is related to the suppression of the large-scale vortex formation near the trailing edge. The Liutex method was applied to visualize the vortical structures for investigating the three-dimensional evolution and instability when interacting with the back wing. The upstream wake triggered dual-secondary vortices and intensified the secondary instability on the back wing. The induced vortices contributed to the lift enhancement because they provided an extra low-pressure region when propagating downstream on the suction side of the back wing. Because of the three-dimensional destabilization, the vortex interaction in the evolution process accelerated the transition and injection of the high-momentum flow into the boundary layer attached to the back wing, energizing the turbulent boundary layer and eliminating the large-scale separation near the trailing edge. This study provided a new perspective on the enhanced aerodynamic performance of tandem layout.

This study employs Direct Numerical Simulation (DNS) to investigate the flow and heat transfer characteristics in a compressor blade passage at five Reynolds numbers ($Re=1.091\times {10}^5$, $1.229\times {10}^5$, $1.367\times {10}^5$, $1.506\times {10}^5$, and $1.645\times {10}^5$). A recent method based on local inviscid velocity reconstruction is applied to define and calculate boundary layer parameters, whereas the Rortex vortex identification method is used to analyze turbulent vortical structures. Results indicate that $Re$ significantly affects separation bubble size, transition location, and reattachment behavior, thereby altering wall heat transfer characteristics. On the pressure surface, separation and early transition are observed at higher $Re$, with the Nusselt number ($Nu$) remaining high after transition. On the suction surfaces, separation occurs such that large-scale separation at low $Re$ reduces $Nu$, while reattachment combined with turbulent mixing at high $Re$ significantly increases $Nu$. Turbulent vortical structures enhance near-wall fluid mixing through induced ejection and sweep events, thereby promoting momentum and heat transport. As $Re$ increases, the vortical structures become denser with reduced scales and the peaks in heat flux move closer to the wall, thus improving convective heat transfer efficiency.

In literary works, there are always disharmonious characters beyond the satisfactory plot of a novel script. Among these characters, the female characters are the most prominent, especially the image of “crazy woman”. They are placed in different times, different scenes and different cultural backgrounds. They are either evil or mad, or sad and mean, or crazy, stupid and irritable. The mad woman in the attic, written by Sandra Gilbert and Susan Guba in 1979, is known as “the Bible of feminist literary criticism in the 20th century”. It analyzes the typical images of “mad woman” in western literary history, which is directly derived from Bertha, the ex-wife in the attic in Jane Eyre. This paper takes three female images in East Asian Literature: Cao Qiqiao in Zhang Ailing’s The Golden Chain, Leng Qiuyue in Chen Zhongshi’s White Deer Plain, and Kim Ji-young in Korean writer Zhao Nanzhu’s Kim Ji-young, Born 1982. The purpose of this paper is to explore why these “crazy women” are imprisoned, where they are imprisoned, why they cannot escape, and how to deal with themselves in different individual dilemmas by combining the specific text analysis and feminist theory. Through the analysis and comparison of the characters, the enlightenment in the current gender consciousness and gender environment is given.

A direct numerical simulation is performed on a T106A linear cascade at a low Reynolds number (Re) of 1.48×104 to investigate the connection between instantaneous structures and instability mechanisms of the trailing-edge laminar separation bubble. A sequential five-vortex pattern is identified, induced by the secondary vortex, comprising the main separation vortex, secondary vortex, braid-region vortex, shedding vortex, and trailing-edge vortex. Two-dimensional waves are investigated in physical and Fourier spaces using a double Fourier transform. The results reveal that the boundary-layer fluctuations are influenced by perturbations from the adjacent blade, and the separated boundary layer exhibits selective responses to waves of different frequencies. High-frequency fluctuations originating from the upstream attached flow are suppressed near the separation point, whereas the absolute and Kelvin–Helmholtz instabilities primarily stimulate the linear growth of two-dimensional fluctuations within the separated boundary layer. The near-wall absolute instability arises from the periodic motion of the secondary vortex, which is generated in both upstream and downstream portions of the primary separation bubble and subsequently convects downstream. The secondary vortex also contributes to the formation of the braid region and the shedding vortex, where three-dimensional fluctuations are generated via the hyperbolic and elliptical secondary instabilities, respectively. In the trailing-edge region, the shedding vortex is locked with the trailing-edge vortex at the fundamental frequency. The corresponding mode is extracted by the dynamic mode decomposition, which demonstrates that the interaction between the trailing-edge and shedding vortices further amplifies the three-dimensional fluctuations.