Vortex shedding from a circular cylinder near a moving ground

The flow and force characteristics have been experimentally investigated of a circular cylinder with an aspect ratio of 8.33, with and without end-plates, placed near and parallel to a moving ground, on which substantially no boundary layer developed to interfere with the cylinder. Mean drag and lift measurements, surface oil flow visualization, and particle image velocimetry (PIV) measurements were carried out at two upper-subcritical Reynolds numbers of 0.4 and 1.0×105 (based on the cylinder diameter d) to investigate the mechanisms of the ground effect, i.e., the effect of the gap-to-diameter ratio h/d, where h is the gap between the cylinder and the ground. For the cylinder with end-plates, on which the oil flow patterns were observed to be essentially two-dimensional, the drag rapidly decreased as h/d decreased to less than 0.5 but became constant for h/d of less than 0.35, unlike that usually observed near a fixed ground. This critical drag behavior was found to be directly related to a global change in the near wake structure of the cylinder; as h/d decreased the Kármán-type vortex shedding became intermittent at h/d=0.4, and then totally ceased and instead two nearly parallel shear layers were formed behind the cylinder at h/d=0.3 and below. For the cylinder without end-plates, however, no such critical change in drag was observed as the Kármán-type vortices were not generated in the near wake region at all h/d investigated. Based on the experimental results obtained, further discussions are also given to the essential cause of the cessation of the Kármán vortex shedding in the ground effect

Comparative studies of circulating KL-6, type III procollagen N-terminal peptide and type IV collagen 7S in patients with interstitial pneumonitis and alveolar pneumonia

AbstractKL-6, a MUC1 mucin preferentially expressed in regenerating type 2 pneumocytes, has been reported to be a sensitive serum marker for evaluating the disease activity of interstitial pneumonitis (IP). Type III procollagen N-terminal peptide (PIIIP) and type IV collagen 7S (7S collagen) have also been reported to be useful in the serological evaluation of the activity. Their levels were measured and their serodiagnostic values were compared simultaneously in patients with IP and alveolar pneumonia. The study population was 45 patients with IP and 12 patients with alveolar pneumonia. Serum KL-6 levels were measured by a specific enzyme immunoassay, and both serum PIIIP and 7S collagen concentrations by their correspondent radioimmunoassay kits. There were no significant difference of serum C-reactive protein level, which was evaluated as an indicator of inflammatory process, between IP and alveolar pneumonia patients. In IP, the abnormally elevated rate of KL-6 [80% (3645)] was significantly higher than those of PIIIP [40% (1845)] and 7S collagen [40% (1845)]. In alveolar pneumonia, the rate of KL-6 [0% (012)] was significantly lower than those of PIIIP [33% (412)] and 7S collagen [25% (312)]. There were no significant correlations among serum levels of the markers. These observations indicate that the serodiagnostic value of KL-6 for IP is superior to that of PIIIP and 7S collagen, and that KL-6 has a characteristic to discriminate IP from alveolar pneumonia

Investigation of the flow in a circular cavity using stereo and tomographic particle image velocimetry

Aerospace Engineerin