Air drag on yarn and package surfaces affects yarn tension, which in turn affects energy consumption and ends-down in ring spinning. This paper investigates the effects of yarn hairiness on air drag in ring spinning. Theoretical models of skin friction coefficient on the surface of rotating yarn packages were developed. The predicted results were verified with experimental data obtained from co...

SUMMARY There is a need for a wave drag method that combines the speed of handbook methods with the accuracy of computational methods. Especially determining the onset of wave drag as well as the initial drag rise is important in initial design stages. Meta-models allow this by capturing the trends present in previously computed data, providing an accurate and fast representation. In this repor...

The glide is a major part of starts, turns and the stroke cycle in breaststroke. Glide performance, indicated by the average velocity, can be improved by increasing the glide efficiency, that is, the ability of the body to minimise deceleration. This paper reviews the factors that affect glide efficiency. In the first part of the review the sources of resistive force are reviewed including surf...

The analytical models of Teixeira et al. (2004) and Teixeira and Miranda (2004), where the gravity wave drag exerted by a sheared stratified flow on axisymmetric or 2D mountains is calculated, are extended here to mountains with an elliptical horizontal cross section. For the simple situations considered in this study, the normalized drag depends on only two parameters: the Richardson number at...

Meso-scale structure existing in the form of particle clusters or strands in concurrent-up gas–solid two-phase flow has been extensively corroborated in experimental research. However, its significant effects on interfacial drag coefficient are seldom taken into account in current computational fluid dynamic (CFD) simulations by using the two-fluid models. The energy-minimization multi-scale (E...

The ice–ocean system is investigated on inertial to monthly time scales using winter 2009–10 observations from the first ice-tethered profiler (ITP) equipped with a velocity sensor (ITP-V). Fluctuations in surface winds, ice velocity, and ocean velocity at 7-m depth were correlated. Observed ocean velocity was primarily directed to the right of the ice velocity and spiraled clockwise while deca...

In competitive swimming, suits have become more important. These suits influence friction, pressure and wave drag. Friction drag is related to the surface properties whereas both pressure and wave drag are greatly influenced by body shape. To find a relationship between the body shape and the drag, the anthropometry of several world class female swimmers wearing different suits was accurately d...

The wintertime northern annular mode (NAM) at the surface is known to undergo slow intraseasonal variations in association with stratospheric variability, which leads the surface signal by up to several weeks. The relative contributions, however, of potentially relevant stratosphere–troposphere coupling mechanisms are not yet fully understood. In this study the relative roles of (i) the downwar...

A computational study was conducted to better understand experimental results obtained from wind tunnel tests of a Mach 4 waverider model and a comparative reference configuration. The experimental results showed that the performance of the reference configuration was slightly better than that of the waverider model. These results contradict waverider design theory, which suggests that a waveri...

Flow at an air-water interface is limited by drag from both the two-dimensional surface and three-dimensional subphase. Separating these contributions to the interfacial drag is necessary to measure surface viscosity as well as to understand the influence of the interface on flow. In these experiments, a magnetic needle floating on a monolayer-covered air-water interface is put in motion by app...