Simulation of unsteady blood flow dynamics in the thoracic aorta

Abstract

In this work, blood flow dynamics was analyzed in a realistic thoracic aorta (TA) model under unsteady-state conditions via velocity contours, secondary flow, pressure and wall shear stress (WSS) distributions. Our results demonstrated that the primary flow velocity is skewed towards the inner wall of the ascending aorta; but this skewness shifts towards the posterior wall in the aortic arch and then towards the anterior-outer wall in the descending aorta. Within the three arch branches, the flow velocity is skewed to the distal walls with flow reversal along the proximal walls. Strong secondary flow motion is observed in the TA, especially at the inlet of the arch branches. WSS is highly dynamic, but was found to be the lowest along the proximal walls of the arch branches. Finally, pressure was found to be low along the inner aortic wall and in the proximal walls of the arch branches, and high around the three stagnation regions distal to the arch branches and along the outer wall of the ascending aorta.Keywords: Blood flow, computational fluid dynamics, hemodynamics, thoracic aorta, wall shear stress. RESUMENEn este trabajo se analiza la dinámica del flujo sanguíneo en un modelo realista de la aorta torácica (TA, por sus siglas en inglés) en condiciones transitorias visualizando las distribuciones de velocidad, flujo secundario, presión y esfuerzos cortantes parietales (WSS). Los resultados obtenidos muestran que la velocidad primaria del flujo tiende hacia la pared interior de la aorta ascendente, pero esta, a su vez, tiende hacia la pared posterior en el arco aórtico y hacia las paredes anterior y exterior en la aorta descendente. En las tres ramificaciones del arco aórtico la velocidad del flujo se acerca hacia las paredes distales mostrando recirculación del flujo en las cercanías de las paredes proximales. En la TA se observa un flujo secundario intenso, especialmente a la entrada de las ramificaciones del arco. Finalmente, la presión es baja a lo largo de la pared interior de la aorta y en las paredes proximales de las ramificaciones, mientras que es alta en las zonas de estancamiento situadas en las paredes distales de las ramificaciones así como a lo largo de la pared exterior de la aorta ascendente.Palabras clave: Flujo sanguíneo, dinámica de fluidos computacional, hemodinámica, aorta torácica, esfuerzos cortantes parietales.

Peak Flow in Model Aorta Through Bi-Leaflet Mechanical Heart Valve with Varying Orientation

“…Contra-rotating tip vortices springing from leaflets are seen well-formed and positioned in accordance with the valve orientation. In the ascending arch at P 6 , the baseline shows characteristic increase in the axial velocity exceeding the inlet velocity toward inner wall, observed from earlier in vitro 1,29,30 and in vivo 7,31 studies, in conjunction with enhanced secondary flow. A large part of the cross section is dominated by a unidirectional secondary flow from the inner wall to the outer wall with decreasing velocity which gets deflected circumferentially along the wall in reverse direction with increasing velocity.…”

Comparison Of Newtonian And Non-Newtonian Blood Flow In Ascending Aortic Aneurysm

“…[14]. A model of a non-Newtonian fluid in the ascending aorta resulted in maximum WSS values of 7.5 Pa during systole and 1.6 Pa during diastole [15]. Furthermore, using the non-Newtonian Carreau model with ANSYS Fluent software yielded a WSS of 32 Pa at systole (maximum blood velocity of 1.6 m/s) in the ascending aneurysm zone [16].…”