Diffusion Coefficients over Rough and Smooth Boundaries, obtained by Measuring the Concentration-Velocity Covariance

A preliminary investigation of the coefficients of turbulent diffusion in an open channel was conducted by employing: 1) hot-film anemometry to detect the velocity fluctuation, 2) a platinized single-electrode conductivity probe to detect the concentration fluctuations, and 3) a digital computing system to evaluate the covariance and other statistical properties of the two output signals. Data were collected downstream of a constant-discharge point source of neutrally-bouyant salt solution at stream temperature and velocity. Using current semi-empirical methods diffusion coefficients were obtained in the vertical and lateral directions as well as dispersion coefficients due to convection

Basic data report on the turbulent spread of heat & matter

CER71-72RSM-9.August 1971.Includes bibliographical references (page 75).United States Dept. of Interior Geological Survey, Water Resources Division in cooperation with the United States Environmental Protection Agency, National Thermal Pollution Research Program.The purpose of this report is to present the results of an investigation of the turbulent transport properties of heated and salt water jets in an open channel flow. The data were taken cooperatively by the U.S. Geological Survey and the Environmental Protection Agency. The data include measurement of the turbulence characteristics, longitudinal dispersion, and vertical and lateral turbulent diffusion. Three different boundary roughnesses were used in the investigation. The turbulence data includes the intensity of turbulence, Eulerian time scales, autocorrelation function distributions, space correlation distributions in the vertical and horizontal directions and space-time correlation function distributions in the longitudinal direction. Vertical and lateral turbulent diffusion data were obtained downstream from jets of three diameters, at four different jet strengths. Two tracer fluids, heated water and a neutrally buoyant salt solution were used. Only basic data are reported here. The extensive analysis of these results will be the subject of a future publication

Principles and Measuring Techniques of Turbulence Characteristics in Open-Channel Flows

Turbulence velocity fluctuations in open-channel shear flows cause or strongly influence a large number of fluid-mechanics phenomena of interest to engineers. Turbulence measurements in fluids have been made with varying degrees of success, but only recently have measurements of turbulence in water been made with any degree of reliability. This recent improvement is due to the development of hot-film anemometry, which has given the researcher a tool for studying the structure of turbulence in open-channel flows. The fine spatial resolution (due to the small size of the sensor) and the good frequency response of the hot-film anemometer system are unmatched by any other system now available for making turbulence measurements in open-channel flows. This report describes the statistical turbulence characteristics that best define the structure of the flow field and the relation between the characteristics and the equations of motion and energy. A detailed description of instrumentation, sensor selection, and theory of operation is presented along with a discussion of calibration characteristics, heat-transfer relations, hot-film and hot-wire measurements, and possible sources of errors in turbulence measurements. The report explains in detail a procedure to circumvent contamination problems so that measurements can be made in natural rivers and streams; it also presents a mathematical and experimental justification for the procedure. Aspects of analog and digital data reduction are discussed along with some guidelines to insure meaningful measurement of turbulence characteristics

Public Interest in Shoulder Platelet-Rich Plasma Injections Is Increasing: A 10-Year Google Trends Analysis

Purpose: To quantify and analyze public interest trends in platelet-rich plasma (PRP) therapy for shoulder pathology between 2011 and 2020 using Google Trends data. Methods: Google Trends data were queried for online search data ranging from January 2011 to December 2020. Various combinations of terms related to PRP and shoulder pathology were queried. Terms related to corticosteroid therapy in association with shoulder pathology were also generated for comparative analysis. Analyses were performed regarding trends in online search volumes. Results: Linear models were generated to evaluated trends in the volume of online searches for PRP and corticosteroid therapy for shoulder pathology. For both the PRP and steroid groups, linear models showed a statistically significant increase in search volume for the period studied (P < .001). The PRP group showed a significantly greater growth rate than the steroid group (P < .001). There were no statistically significant differences in online search volume when compared between different geographic and socioeconomic locations. Conclusions: This study indicates consistently increasing public interest in PRP injections in the shoulder. The rate of online search volume growth of PRP is significantly greater than that of corticosteroid injections for the period studied. Clinical Relevance: Awareness of patient perceptions has value in informing shared decision making, aligning patient expectations, and guiding areas of future research. Each of these has an impact on patient care. Being aware of patient interest and expectations is particularly important in areas with controversial or emerging research