A New Computational Fluid Dynamics Method for In‐Depth Investigation of Flow Dynamics in Roller Pump Systems

Abstract

Roller pumps are commonly used in circulatory assist devices to deliver blood, but the inherent high mechanical stresses (especially wall shear stress) may cause considerable damage to cells. Conventional experimental approaches to evaluate and reduce device-induced cell damage require considerable effort and resources. In this work, we describe the use of a new computational fluid dynamics method to more effectively study roller pump systems. A generalized parametric model for the fluid field in a typical roller pump system is presented first, and analytical formulations of the moving boundary are then derived. Based on the model and formulations, the dynamic geometry and mesh of the fluid field can be updated automatically according to the time-dependent roller positions. The described method successfully simulated the pulsing flow generated by the pump, offering a convenient way to visualize the inherent flow pattern and to assess shear-induced cell damage. Moreover, the highly reconfigurable model and the semiautomated simulation process extend the usefulness of the presented method to a wider range of applications. Comparison studies were conducted, and valuable indications about the detailed effects of structural parameters and operational conditions on the produced wall shear stress were obtained. Given the good consistency between the simulated results and the existing experimental data, the presented method displays promising potential to more effectively guide the development of improved roller pump systems which produce less mechanical damage to cells.

Pulsatility Produced by the Hemodialysis Roller Pump as Measured by Doppler Ultrasound

“…The present study showed that high pulsatility does not exist at the arterial needle due to the counteracting force of blood pressure and the compressibility of the tubing indi- Microemboli have been reported to enter the circulation and deposit in the lungs and brain which can cause tissue ischemia and neurological conditions (8)(9)(10). A computational optimization of a roller pump has shown that increasing the number of rollers can produce more uniform and steady flow conditions and reduces the instantaneous maximum velocity (21). It is therefore imperative to determine the source, and implement methods to prevent their passage through the extracorporeal circuit and into the patient.…”

“…It is this phenomenon that causes the extracorporeal tubing to pulse. This instantaneous flow reversal has previously been visualized in a fluid-structure simulation (21). The venous air trap is the most effective mechanism in the circuit at removing this pulse.…”

“…If cavitation is occurring at the pump, the use of multiple rollers coupled with a reduced compression of the tubing may reduce the pressure drop and prevent the total occlusion and subsequent flow reversal that was observed. A computational optimization of a roller pump has shown that increasing the number of rollers can produce more uniform and steady flow conditions and reduces the instantaneous maximum velocity (21). However, further investigation is required to determine if cavitation at the pump is the source of microbubble formation in the hemodialysis extracorporeal circuit.…”

Development of a Double-Lumen Cannula for a Percutaneous RVAD

“…A long-term animal study is required to assess whether there is any potential for valve damage. Thrombosis in the RJV after use of the Avalon Elite has been reported 31 . Although this thrombosis may be removed by a minor surgery during DLC withdrawal 31 , this potential drawback may dampen enthusiasm for the pRVAD DLC since the RJV is a frequent site for endomyocardial biopsies following heart transplant.…”

Vibration-Based Experimental Identification of the Elastic Moduli Using Plate Specimens of the Olive Tree

“…This effect as a function of the length-to-thickness ratio. It has been noted by different authors [25][26][27][28] that the transverse shear effect:…”