No abstract

The primary focus of this research is the design of wall-driven peristaltic pumps based on first principles with minimal simplifying assumptions and implementation by numerical simulation. Peristaltic pumps are typically used to pump clean/sterile fluids because crosscontamination with exposed pump components cannot occur. Some common biomedical applications include pumping IV fluids through an infusion device and circulating blood by means of heart-lung machines during a bypass surgery. The specific design modality described here involves the structural analysis of a hyperelastic tube-wall medium implemented by numerical simulation. The numerical solutions yielded distributions of stresses and mechanical deflections. In particular, the applied force needed to sustain the prescribed rate of compression was determined. From numerical information about the change of the volume of the bore of the tube, the rate of fluid flow provided by the peristaltic pumping action was calculated and several algebraic equation fits are presented. Other results of practical utility include the spatial distributions of effective stress (von Mises) at a succession of times during the compression cycle and the corresponding information for the spatial and temporal evolution of the displacements.

Purpose The study described here aims to set forth an analysis approach for a specific biomedical therapeutic device principally involving fluid mechanics and resulting sound generation. The function of the therapeutic device is to clear mucus from the airways of the lungs. Clearance of the airways is a primary means of relief for cystic fibrosis and is also effective in less profound dysfunctions such as asthma. The complete system consists of a device to periodically pulse air pressure and a vest that girdles the abdomen of the patient and receives and discharges the pulsating airflow. The source of pulsed air can be tuned both with respect to the amplitude and frequency of the pressure pulsations. Design/methodology/approach The key design tools used here are computational fluid dynamics and the theory of turbulence-based sound generation. The fluid flow inside of the device is multidimensional, unsteady and turbulent. Findings Results provided by the fluid mechanic study include the rates of fluid flow between the device and the inflatable vest, the rates of air supplied to and extracted from the device, the fluid velocity magnitudes and directions that result from the geometry of the device and the magnitude of the turbulence generated by the fluid motion and the rotating component of the device. Both the velocity magnitudes and the strength of the turbulence contribute to the quantitative evaluation of the sound generation. Originality/value A comprehensive literature search on this type of therapeutic device to clear mucus from the airways of the lungs revealed no previous analysis of the fluid flow and sound generation inside of the device producing the pulsed airflow. The results presented in this paper pinpoint the locations and causes of sound generation that can cause audible discomfort for patients.