Researcher: Rasooli, Reza
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Rasooli, Reza
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Publication Metadata only Infusion jet flow control in neonatal double lumen cannulae(Asme, 2020) Yıldız, Yahya; Department of Mechanical Engineering; Department of Mechanical Engineering; Department of Mechanical Engineering; Rasooli, Reza; Jamil, Muhammad; Pekkan, Kerem; Researcher; Researcher; Faculty Member; Department of Mechanical Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; N/A; 161845Clinical success of extracorporeal membrane oxygenation (ECMO) depends on the proper venous cannulation. Venovenous (VV) ECMO is the preferred clinical intervention as it provides a single-site access by utilizing a VV double lumen cannula (VVDLC) with a higher level of mobilization and physical rehabilitation. Concurrent venous blood drainage and oxygenated blood infusion in the right atrium at the presence of the cannula makes the flow dynamics complex where potential mixing of venous and oxygenated blood can drastically decrease the overall performance of ECMO. There are no studies focusing on the neonatal and pediatric populations, in which the flow related effects are critical due to the small atrium size. In this study, fluid dynamics of infusion outflow jet for two commercially available neonatal VVDLC is analyzed using particle image velocimetry (PIV). Moreover, six new designs are proposed for the infusion channel geometry and compared. Important flow parameters such as flow turning angle (FTA), velocity decay, potential core, and turbulent intensity are investigated for the proposed models. The experiments showed that the outflow parameters of commercial cannulae such as FTA are strongly dependent on the operating Re number. This may result in a drastic efficiency reduction for cannula operating at off-design flow conditions. Moreover, the infusion outlet tip structure and jet internal guiding pathway (JIGP) was observed to greatly affect the outflow flow features. This is of paramount importance since the anatomical positioning of the cannula and the infusion outlet is strongly dependent on the outflow properties such as FTA.Publication Metadata only Heart valve inspired and multi-stream aortic cannula: novel designs for cardiopulmonary bypass improvement in neonates(Wiley, 2019) Department of Mechanical Engineering; Department of Mechanical Engineering; Rasooli, Reza; Pekkan, Kerem; Researcher; Faculty Member; Department of Mechanical Engineering; College of Engineering; College of Engineering; N/A; 161845In a typical open-heart surgery, the blood flow through the aortic cannula is a critical element of the cardiopulmonary bypass (CPB) procedure. Especially for the neonatal and pediatric CPB flow conditions, the need for small hydraulic diameter and large blood flow results confined turbulent jet flow regimes that exacerbate blood damage and platelet activation. Simultaneously, the confined jet wake leads to complex stagnation and recirculating flows that cause considerable thrombosis, blood, and endothelial cell damage through the aorta. Thus, an ideal neonatal CPB cannula should be able to generate optimal jet expansion so that sufficient cerebral perfusion is achieved through the head-neck vessels to avoid postoperative neurological complications and developmental defects in children. To address these challenges, a formal bio-inspired design framework is conducted to reach the desired cannula function through novel analogous biological components, first-time in literature. Among the biological jet flow regimes studied, the ventricle filling-jet generated through the atrio-ventricle (AV) valves are found to be the most promising. Inspired from human AV valve shapes, 8 different novel cannula designs, considering the size constrains of neonatal and pediatric patients are built via high-accurate micro stereo-lithography. Using 2-dimensional time-resolved particle image velocimetry the turbulent jet wake characteristics are measured and compared. The proposed designs have exhibited a significant improvement as compared to standard circular cannula by around 30% reduction in maximum outflow velocity and more than 80% reduction in potential core length and spatial energy dissipation which results in a lower risk of cardiovascular and blood damage.Publication Metadata only Hemodynamics of neonatal double lumen cannula malposition(2020) Yıldız, Yahya; Salihoğlu, Ece; Department of Mechanical Engineering; Department of Mechanical Engineering; Department of Mechanical Engineering; Department of Mechanical Engineering; Department of Mechanical Engineering; Jamil, Muhammad; Rezaeimoghaddam, Mohammad; Çakmak, Bilgesu; Rasooli, Reza; Pekkan, Kerem; Researcher; Researcher; Researcher; Researcher; Faculty Member; Department of Mechanical Engineering; College of Engineering; College of Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; N/A; 161845Objective: Malposition of dual lumen cannula is a frequent and challenging complication in neonates and plays a significant role in shaping the in vitro device hemodynamics. This study aims to analyze the effect of the dual lumen cannula malposition on right-atrial hemodynamics in neonatal patients using an experimentally validated computational fluid dynamics model. Methods: A computer model was developed for clinically approved dual lumen cannula (13Fr Origen Biomedical, Austin, Texas, USA) oriented inside the atrium of a 3-kg neonate with normal venous return. Atrial hemodynamics and dual lumen cannula malposition were systematically simulated for two rotations (antero-atrial and atrio-septal) and four translations (two intravascular movements along inferior vena cava and two dislodged configurations in the atrium). A multi-domain compartmentalized mesh was prepared to allow the site-specific evaluation of important hemodynamic parameters. Transport of each blood stream, blood damage levels, and recirculation times are quantified and compared to dual lumen cannula in proper position. Results: High recirculation levels (39 ± 4%) in malpositioned cases resulted in poor oxygen saturation where maximum recirculation of up to 42% was observed. Apparently, Origen dual lumen cannula showed poor inferior vena cava bloodcapturing efficiency (48 ± 8%) but high superior vena cava blood–capturing efficiency (86 ± 10%). Dual lumen cannula malposition resulted in corresponding changes in residence time (1.7 ± 0.5 seconds through the tricuspid). No significant differences in blood damage were observed among the simulated cases compared to normal orientation. Compared to the correct dual lumen cannula position, both rotational and translational displacements of the dual lumen cannula resulted in significant hemodynamic differences. Conclusion: Rotational or translational movement of dual lumen cannula is the determining factor for atrial hemodynamics, venous capturing efficiency, blood residence time, and oxygenated blood delivery. Results obtained through computational fluid dynamics methodology can provide valuable foresight in assessing the performance of the dual lumen cannula in patient-specific configurations.Publication Metadata only In vitro measurement of hepatic flow distribution in Fontan vascular conduits: towards rapid validation techniques(Elsevier, 2022) Köse, Banu; Şaşmazel, Ahmet; Department of Mechanical Engineering; Department of Mechanical Engineering; Department of Mechanical Engineering; Rasooli, Reza; Lashkarinia, Seyedeh Samaneh; Pekkan, Kerem; Researcher; Researcher; Faculty Member; Department of Mechanical Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; N/A; 161845Fontan operation is the last stage of single-ventricle surgical reconstructions that connects superior and inferior vena cava (SVC, IVC) to the pulmonary arteries. The key design objectives in total cavopulmonary connections (TCPC) are to achieve low power loss (PL) and balanced hepatic flow distribution (HFD). Computational fluid dynamics (CFD) played a pivotal role in pre-surgical design of single-ventricle patients. However, the clinical application of current CFD techniques is limited due to their complexity, high computational time and untested accuracy for HFD prediction. This study provides a performance assessment of computationally low-cost steady Reynolds-Averaged Navier-Stokes (RANS) k-epsilon turbulent models for simulation of Fontan hemodynamics. The performance is evaluated based on prediction accuracy for three clinically important Fontan hemodynamic indices: HFD, PL and total pulmonary flow split (TPFS). For this purpose, a low-cost experimental technique is developed for rapid quantification of Fontan performance indices. Experiments and simulations are performed for both an idealized and a complex 3D reconstructed patient-specific TCPC. Time-averaged flow data from phase contrast MRI was used as the boundary conditions for the patient-specific model. For the idealized model, different SVC/IVC flow ratios corresponding to different cardiac outputs and Reynolds' numbers were examined. This study revealed that steady RANS k-epsilon models are able to estimate the Fontan hemodynamic indices with acceptable accuracy within minutes. Among these, standard k-epsilon two-layer was found to deliver the best agreement with the in vitro data with an average error percentage of 1.7, 2.0 and, 3.9 for HFD, TPFS and, PL, respectively for all cases.Publication Metadata only Hemodynamic performance limits of the neonatal double-lumen cannula(Elsevier, 2021) Yıldız, Yahya; Salihoğlu, Ece; Department of Mechanical Engineering; Department of Mechanical Engineering; Department of Mechanical Engineering; Department of Mechanical Engineering; Rasooli, Reza; Jamil, Muhammad; Rezaeimoghaddam, Mohammad; Pekkan, Kerem; Researcher; Researcher; Researcher; Faculty Member; Department of Mechanical Engineering; College of Engineering; College of Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; 161845Venovenous extracorporeal membrane oxygenation (VV-ECMO) is the preferred surgical intervention for patients suffering from severe cardiorespiratory failure, also encountered in SARS-Cov-2 management. The key component of VV-ECMO is the double-lumen cannula (DLC) that enables single-site access. The biofluid dynamics of this compact device is particularly challenging for neonatal patients due to high Reynolds numbers, tricuspid valve location and right-atrium hemodynamics. In this paper we present detailed findings of our comparative analysis of the right-atrial hemodynamics and salient design features of the 13Fr Avalon Elite DLC (as the clinically preferred neonatal cannula) with the alternate Origen DLC design, using experimentally validated computational fluid dynamics. Highly accurate 3D reconstructions of both devices were obtained through an integrated optical coherence tomography and micro-CT imaging approach. Both cannula configurations displayed complex flow structures inside the atrium, superimposed over predominant recirculation regimes. We found that the Avalon DLC performed significantly better than the Origen alternative, by capturing 80% and 94% of venous blood from the inferior and superior vena cavae, respectively and infusing the oxygenated blood with an efficiency of more than 85%. The micro-scale geometric design features of the Avalon DLC that are associated with superior hemodynamics were investigated through 14 parametric cannula configurations. These simulations showed that the strategic placement of drainage holes, the smooth infusion blood stream diverter and efficient distribution of the venous blood capturing area between the vena cavae are associated with robust blood flow performance. Nevertheless, our parametric results indicate that there is still room for further device optimization beyond the performance measurements for both Avalon and Origen DLC in this study. In particular, the performance envelope of malpositioned cannula and off-design conditions require additional blood flow simulations for analysis.Publication Metadata only Patient-specific atrial hemodynamics of a double lumen neonatal cannula in correct caval position(Wiley, 2018) Salihoglu, Ece; Yildiz, Yahya; N/A; Department of Mechanical Engineering; N/A; Department of Mechanical Engineering; Department of Mechanical Engineering; Jamil, Muhammad; Rezaeimoghaddam, Mohammad; Çakmak, Bilgesu; Rasooli, Reza; Pekkan, Kerem; Researcher; Researcher; PhD Student; Researcher; Faculty Member; Department of Mechanical Engineering; N/A; College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; College of Engineering; N/A; N/A; N/A; 161845Clinical success of pediatric veno-venous (VV) extracorporeal membrane oxygenation (ECMO) is associated with the double lumen cannula cardiovascular device design as well as its anatomic orientation in the atrium. The positions of cannula ports with respect to the vena cavae and the tricuspid valve are believed to play a significant role on device hemodynamics. Despite various improvements in ECMO catheters, especially for the neonatal and congenital heart patients, it is still challenging to select a catalogue size that would fit to most patients optimally. In effect, the local unfavorable blood flow characteristics of the cannula would translate to an overall loss of efficiency of the ECMO circuit. In this study, the complex flow regime of a neonatal double lumen cannula, positioned in a patient-specific right atrium, is presented for the first time in literature. A pulsatile computational fluid dynamics (CFD) solver that is validated for cardiovascular device flow regimes was used to perform the detailed flow, oxygenated blood transport, and site-specific blood damage analysis using an integrated cannula and right atrium model. A standard 13Fr double lumen cannula was scanned using micro-CT, reconstructed and simulated under physiologic flow conditions. User defined scalar transport equations allowed the quantification of the mixing and convection of oxygenated and deoxygenated blood as well as blood residence times and hemolysis build-up. Site-specific CFD analysis provided key insight into the hemodynamic challenges encountered in cannula design and the associated intra-atrial flow patterns. Due to neonatal flow conditions, an ultra high velocity infusion jet emanated from the infusion port and created a zone of major recirculation in the atrium. This flow regime influenced the delivery of the oxygenated blood to the tricuspid valve. Elevated velocities and complex gradients resulted in higher wall shear stresses (WSS) particularly at the infusion port having the highest value followed by the aspiration hole closest to the drainage port. Our results show that, in a cannula that is perfectly oriented in the atrium, almost 38% of the oxygenated blood is lost to the atrial circulation while only half of the blood from inferior vena cava (IVC) can reach to the tricuspid valve. As such, approximately 6% of venous blood from superior vena cava (SVC) can be delivered to tricuspid. High values of hemolysis index were observed with blood damage encountered around infusion hole (0.025%). These results warrant further improvements in the cannula design to achieve optimal performance of ECMO and better patient outcomes.Publication Open Access Estimation of pulsatile energy dissipation in intersecting pipe junctions using inflow pulsatility indices(American Institute of Physics (AIP) Publishing, 2021) Dur, Onur; Department of Mechanical Engineering; Pekkan, Kerem; Rasooli, Reza; Faculty Member; Researcher; Department of Mechanical Engineering; Graduate School of Health Sciences; College of Engineering; 161845; N/AThis study aims to characterize the effect of inflow pulsatility on the hydrodynamic power loss inside intersecting double-inlet, double-outlet pipe intersection (DIPI) with cross-flow mixing. An extensive set of computational fluid dynamics (CFD) simulations was performed in order to identify the individual effects of flow pulsatility parameters, i.e., amplitude, frequency, and relative phase shift between the inflow waveform oscillations, on power loss. An experimentally validated second order accurate solver is employed in this study. To predict the pulsatile flow performance of any given arbitrary inflow waveforms, we proposed three easy-to-calculate pulsatility indices. The frequency-coupled quasi-steady flow theory is incorporated to identify the functional form of pulsatile power loss as a function of these indices. Our results indicated that the power loss within the inflow branch sections, lumped outflow-junction section, and the whole conduit correlates strongly with the pulsatility of each inflow waveform, the total inflow pulsatility, and inflow frequency content, respectively. The complete CFD simulation matrix provided a unified analytical expression that predicts pulsatile power loss inside a one-degree offset DIPI geometry. The predictive accuracy of this expression is evaluated in comparison to the CFD evaluation of arbitrary multi-harmonic inflow waveforms. These results have important implications on hydrodynamic pipe networks that employ complex junctions as well as in the patient-to-patient comparison of surgically created vascular connections. Coupling the present analytical pulsatile power loss expression with non-dimensional steady power loss formulation provided a valuable predictive tool to estimate the pulsatile energy dissipation for any arbitrary junction geometry with minimum use of the costly CFD computations.Publication Open Access A novel Fontan Y-graft for interrupted inferior vena cava and azygos continuation(Oxford University Press (OUP), 2022) Çicek, Murat; Köse, Banu; Yılmaz, Emine Hekim; Aydemir, Numan Ali; Özkök, Serçin; Yurtseven, Nurgül; Erdem, Hasan; Sasmazel, Ahmet; Department of Mechanical Engineering; Lashkarinia, Seyedeh Samaneh; Pekkan, Kerem; Rezaeimoghaddam, Mohammad; Rasooli, Reza; Faculty Member; Researcher; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 161845; N/A; N/AObjectives: to evaluate the hemodynamicdynamic advantage of a new Fontan surgical template that is intended for complex single-ventricle patients with interrupted inferior vena cava-azygos and hemi-azygos continuation. The new technique has emerged from a comprehensive pre-surgical simulation campaign conducted to facilitate a balanced hepatic flow and somatic Fontan pathway growth after Kawashima procedure. Methods: for 9 patients, aged 2 to 18 years, majority having poor preoperative oxygen saturation, a pre-surgical computational fluid dynamics customization is conducted. Both the traditional Fontan pathways and the proposed novel Y-graft templates are considered. Numerical model was validated against in vivo phase-contrast magnetic resonance imaging data and in vitro experiments. Results: the proposed template is selected and executed for 6 out of the 9 patients based on its predicted superior hemodynamic performance. Pre-surgical simulations performed for this cohort indicated that flow from the hepatic veins (HEP) do not reach to the desired lung. The novel Y-graft template, customized via a right- or left-sided displacement of the total cavopulmonary connection anastomosis location resulted a drastic increase in HEP flow to the desired lung. Orientation of HEP to azygos direct shunt is found to be important as it can alter the flow pattern from 38% in the caudally located direct shunt to 3% in the cranial configuration with significantly reversed flow. The postoperative measurements prove that oxygen saturation increased significantly (P-value = 0.00009) to normal levels in 1 year follow-up. Conclusions: the new Y-graft template, if customized for the individual patient, is a viable alternative to the traditional surgical pathways. This template addresses the competing hemodynamic design factors of low physiological venous pressure, high postoperative oxygen saturation, low energy loss and balanced hepatic growth factor distribution possibly assuring adequate lung development.Publication Open Access Thrust and hydrodynamic efficiency of the bundled flagella(Multidisciplinary Digital Publishing Institute (MDPI), 2019) Danış, Ümit; Chen, Chia-Yuan; Dur, Onur; Department of Mechanical Engineering; Pekkan, Kerem; Sitti, Metin; Rasooli, Reza; Faculty Member; Faculty Member; Researcher; Department of Mechanical Engineering; Graduate School of Sciences and Engineering; 161845; N/A; N/AThe motility mechanism of prokaryotic organisms has inspired many untethered microswimmers that could potentially perform minimally invasive medical procedures in stagnant fluid regions inside the human body. Some of these microswimmers are inspired by bacteria with single or multiple helical flagella to propel efficiently and fast. For multiple flagella configurations, the direct measurement of thrust and hydrodynamic propulsion efficiency has been challenging due to the ambiguous mechanical coupling between the flow field and mechanical power input. To address this challenge and to compare alternative micropropulsion designs, a methodology based on volumetric velocity field acquisition is developed to acquire the key propulsive performance parameters from scaled-up swimmer prototypes. A digital particle image velocimetry (PIV) analysis protocol was implemented and experiments were conducted with the aid of computational fluid dynamics (CFD). First, this methodology was validated using a rotating single-flagellum similitude model. In addition to the standard PIV error assessment, validation studies included 2D vs. 3D PIV, axial vs. lateral PIV and simultaneously acquired direct thrust force measurement comparisons. Compatible with typical micropropulsion flow regimes, experiments were conducted both for very low and higher Reynolds (Re) number regimes (up to a Re number = 0.01) than that are reported in the literature. Finally, multiple flagella bundling configurations at 0 degrees, 90 degrees and 180 degrees helical phase-shift angles were studied using scaled-up multiple concentric flagella thrust elements. Thrust generation was found to be maximal for the in-phase (0 degrees) bundling configuration but with similar to 50% lower hydrodynamic efficiency than the single flagellum. The proposed measurement protocol and static thrust test-bench can be used for bio-inspired microscale propulsion methods, where direct thrust and efficiency measurement are required.