Roughly half of the U.S. public thinks that torture can be acceptable in counterterrorism. According to recent research, dramatic depictions of torture increase public support for the practice. Yet we do not know how frequently—and in what context—torture is depicted across popular media. What messages about the acceptability and effectiveness of torture do Americans receive when they watch popular films? To address this question, we coded each incident of torture in the twenty top-grossing films each year from 2008 to 2017 to analyze how torture is portrayed in terms of its frequency, efficacy, and social acceptability. Results show that the majority of popular films—including films aimed toward children—have at least one torture scene. Across films, the messages sent about torture are fairly consistent. As expected, movies tend to depict torture as effective. Further, how movies portray torture is also a function of who is perpetrating it. Specifically, protagonists are more likely to torture for instrumental reasons or in response to threats and are more likely to do so effectively. In contrast, antagonists are more likely to use torture as punishment and to torture women. The frequency and nature of torture’s depiction in popular films may help explain why many in the public support torture in counterterrorism.

The fluid–structure interactions (FSI) of compliant lifting surfaces is complicated by free-surface and multiphase flows such as cavitation and ventilation. This paper describes the dynamic FSI response of a flexible surface-piercing hydrofoil in dry, wetted, ventilating and cavitating conditions. Experimental modal analysis is used to quantify the resonant frequencies and damping ratios of the fluid–structure system in each flow regime. The generalized hydrodynamic stiffness, fluid damping and fluid added mass are also determined as ratios to the corresponding structural modal forces. Added mass increases with increasing partial immersion of the hydrofoil and decreases in the presence of gaseous cavities. In particular, modal frequencies were observed to increase significantly in fully ventilated flow compared to fully wetted flow. The modal frequencies varied non-monotonically with speed in fully wetted flow. Gaseous cavities reduced the modal added mass and reduced the fluid disturbing force. Modal damping increases non-monotonically with increasing immersion depth. Forward speed causes the fluid damping force to increase with an approximately quadratic functional behaviour, consistent with a series expansion of the Morison equation, although damping identification became increasingly difficult at high flow speeds. The results indicate that fluid damping is greater than the associated structural damping in a quiescent liquid, and increasingly so with increasing immersion, suggesting viscous dissipation as a dominant mechanism. A preliminary investigation of modal vibration as a means of controlling the size and stability of ventilated cavities indicates that low-order modes encourage the formation of ventilation, while higher-order modes encourage the washout and elimination of ventilation.

Compliant lift-generating surfaces have widespread applications as marine propellers, hydrofoils and control surfaces, and the fluid–structure interactions (FSI) of such systems have important effects upon their performance and stability. Multi-phase flows like cavitation and ventilation alter the hydrodynamic and hydroelastic behaviours of lifting surfaces in ways that are not yet completely understood. This paper describes experiments on one rigid and two flexible variants of a vertical surface-piercing hydrofoil in wetted, ventilating and cavitating conditions. Tests were conducted in a towing tank and a free-surface cavitation channel. This work, which is Part 1 of a two-part series, examines the passive, or flow-induced, fluid–structure interactions of the hydrofoils. Four characteristic flow regimes are described: fully wetted, partially ventilated, partially cavitating and fully ventilated. Hydroelastic coupling is shown to increase the hydrodynamic lift and yawing moments across all four flow regimes by augmenting the effective angle of attack. The effective angle of attack, which was derived using a beam model to account for the effect of spanwise twisting deflections, effectively collapses the hydrodynamic load coefficients for the three hydrofoils. A generalized cavitation parameter, using the effective angle of attack, is used to collapse the lift and moment coefficients for all trials at a single immersed aspect ratio, smoothly bridging the four distinct flow regimes. None of the hydrofoils approached the static divergence condition, which occurs when the hydrodynamic stiffness negates the structural stiffness, but theory and experiments both show that ventilation increases the divergence speed by reducing the hydrodynamic twisting moment about the elastic axis. Coherent vortex shedding from the blunt trailing edge of the hydrofoil causes vortex-induced vibration at an approximately constant Strouhal number of 0.275 (based on the trailing edge thickness), and leads to amplified response at lock-in, when the vortex-shedding frequency approaches one of the resonant modal frequencies of the coupled fluid–structure system.