scholarly journals An Accelerated Thrombosis Model for Computational Fluid Dynamics Simulations in Rotary Blood Pumps

2022 ◽  
Author(s):  
Christopher Blum ◽  
Sascha Groß-Hardt ◽  
Ulrich Steinseifer ◽  
Michael Neidlin
Keyword(s):  
Clinical Data ◽  
Computational Models ◽  
Thrombus Formation ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Model Parameters ◽  
Dynamic Simulations ◽  
Heartmate Ii ◽  
Blood Pumps ◽  
Rotary Blood Pumps

Abstract Purpose Thrombosis ranks among the major complications in blood-carrying medical devices and a better understanding to influence the design related contribution to thrombosis is desirable. Over the past years many computational models of thrombosis have been developed. However, numerically cheap models able to predict localized thrombus risk in complex geometries are still lacking. The aim of the study was to develop and test a computationally efficient model for thrombus risk prediction in rotary blood pumps. Methods We used a two-stage approach to calculate thrombus risk. The first stage involves the computation of velocity and pressure fields by computational fluid dynamic simulations. At the second stage, platelet activation by mechanical and chemical stimuli was determined through species transport with an Eulerian approach. The model was compared with existing clinical data on thrombus deposition within the HeartMate II. Furthermore, an operating point and model parameter sensitivity analysis was performed. Results Our model shows good correlation (R2 > 0.93) with clinical data and identifies the bearing and outlet stator region of the HeartMate II as the location most prone to thrombus formation. The calculation of thrombus risk requires an additional 10–20 core hours of computation time. Conclusion The concentration of activated platelets can be used as a surrogate and computationally low-cost marker to determine potential risk regions of thrombus deposition in a blood pump. Relative comparisons of thrombus risk are possible even considering the intrinsic uncertainty in model parameters and operating conditions.

scholarly journals An accelerated thrombosis model for computational fluid dynamics simulations in rotary blood pumps

2021 ◽  
Author(s):  
Christopher Blum ◽  
Sascha Groß-Hardt ◽  
Ulrich Steinseifer ◽  
Michael Neidlin
Keyword(s):  
Platelet Activation ◽  
Clinical Data ◽  
Thrombus Formation ◽  
Fluid Dynamic ◽  
Surrogate Marker ◽  
Blood Pump ◽  
Funding Agency ◽  
Heartmate Ii ◽  
Blood Pumps ◽  
Rotary Blood Pumps

AbstractPurposeThrombosis is one of the major complications in blood-carrying medical devices and a better understanding to influence design of such devices is desirable. Over the past years many computational models of thrombosis have been developed. However, open questions remain about the applicability and implementation within a pump development process. The aim of the study was to develop and test a computationally efficient model for thrombus risk prediction in rotary blood pumps.MethodsWe used a two-stage approach to calculate thrombus risk. At the first stage, the velocity and pressure fields were computed by computational fluid dynamic (CFD) simulations. At the second stage, platelet activation by mechanical and chemical stimuli was determined through species transport with an Eulerian approach. The model was implemented in ANSYS CFX and compared with existing clinical data on thrombus deposition within the HeartMate II.ResultsOur model shows good correlation (R2>0.94) with clinical data and identifies the bearing and outlet stator region of the HeartMate II as the location most prone to thrombus formation. The calculation of platelet activation requires an additional 10-20 core hours of computation time.DiscussionThe concentration of activated platelets can be used as a surrogate marker to determine risk regions of thrombus deposition in a blood pump. Model expansion, e.g. by including more chemical species can easily be performed. We make our model openly available by implementing it for the FDA benchmark blood pump.DeclarationsFundingThis research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors. Open access funding enabled and organized by Projekt DEAL.Conflict of interestAll of the authors have nothing to disclose.Availability of data and materialThe raw data can be retrieved by request from the authors.Code availabilityThe implementation of the thrombus model in the FDA benchmark blood pump geometry is available on https://doi.org/10.5281/zenodo.5116063.Authors’ contributionsAll authors contributed to the study conception and design. CB developed the numerical model, performed the simulations, gathered, analysed and discussed the results. SGH, MN and US were involved in the analysis and discussion of the results. MN supervised the project. MN and CB wrote the manuscript based on the input of all co-authors. All co-authors read and approved the final version of the manuscript.

Simulation of Thrombus Formation Process Using Lattice Boltzmann Method With Consideration of Adhesion Force to Wall

2010 ◽  
Author(s):  
Masaaki Tamagawa
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Adhesion Force ◽  
Thrombus Formation ◽  
Artificial Organs ◽  
Physical Parameters ◽  
Physical Factors ◽  
Blood Pumps ◽  
Boltzmann Method ◽  
Rotary Blood Pumps

Recently artificial organs, especially rotary blood pumps, have been developed in the worldwide, but in this development, thrombus occurs in the pumps. In general, the main physical factors of thrombus formation are considered to be shear rate, wall properties for blood’s adhesion. But, there are no proper CFD codes for predicting thrombus formations using physical parameters in shear flows. In this paper, new model for predicting thrombus formation by considering aggregation and adhesion force to the wall by lattice Boltzmann method is proposed, and the trend of thrombus’s adhesion to the wall can be simulated more adequately than that of previous one.

scholarly journals Fluid-dynamic study of the behavior of the air inside a textile Stenter

2021 ◽  
Vol 2118 (1) ◽  
pp. 012006
Author(s):  
J W Parra ◽  
M B Quadri ◽  
D C Rodríguez
Keyword(s):  
Finite Element Method ◽  
Turbulence Model ◽  
Textile Industry ◽  
Fluid Dynamic ◽  
High Energy ◽  
Operating Conditions ◽  
The Finite Element Method ◽  
Dynamic Simulations ◽  
3D Geometry ◽  
High Energy Consumption

Abstract In the textile industry, drying is one of the most important processes. This process requires large investments and high energy consumption, which generates high costs for companies in this sector. In this work, a modeling of the behavior of the air was carried out in a textile Stenter, under real operating conditions through the development of fluid-dynamic simulations. For the computational modeling of the problem, a 3D geometry was constructed based on measurements taken from an injector of a textile Stenter. The standard k-ε turbulence model was used in the turbulent flow solution. The equations of the model were solved numerically using the finite element method. The standard k-ϵ turbulence model proved to be a model capable of reproducing the behavior of the air in the injectors of the textile Stenter.

Analysis of the Oil Squeezing Power Losses of a Spur Gear Pair by Mean of CFD Simulations

2012 ◽  
Author(s):  
Franco Concli ◽  
Carlo Gorla
Keyword(s):  
High Efficiency ◽  
Fluid Dynamic ◽  
Axial Direction ◽  
Spur Gear ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Main Concern ◽  
Power Losses ◽  
Dynamic Simulations ◽  
Gear Mesh

Efficiency is becoming more and more a main concern in the design of power transmissions and the demand for high efficiency gearboxes is continuously increasing. Also the new restrictive euro standards for the reduction of pollutant emissions from light vehicles impose to improve the efficiency of the engines but also of the gear transmissions. For this reason the resources dedicated to this goal are continuously increasing. The first step to improve efficiency is to have appropriate models to compare different design solutions. Even if the efficiency of transmissions is quit high if compared to the efficiency of the engines and appropriate models to predict the power losses due to gear meshing, to bearings and to seals already exist, in order to have a further improvement, some aspects like the power losses related to the oil churning, oil squeezing and windage are still to be investigated. These losses rise from the interaction between the moving or rotating elements of the transmission and the lubricant. In previous papers [39, 40, 41 43, 44], the authors have investigated the churning losses of planetary speed reducers (in which there is a relative motion between the “planets + planet carrier” and the lubricant). This report is focused on the oil squeezing power losses. This kind of losses is associated with the pumping of the oil at the gear mesh, where there is a contraction of the volume between the mating gears due to the rotation of them and a consequent overpressure. This overpressure implies a fluid flow primarily in the axial direction and this, for viscous fluids, means additional power losses and a decrease of the efficiency. In this work this phenomena has been studied by means of some CFD (computational fluid dynamic) simulations with a VOF (volume of fluid) approach. The influence of some operating conditions like the rotational speed and the lubricant temperature have been studied. The results of this study have been included in a model to predict the efficiency of the whole transmission.

Systematic Parameter Estimation and Sensitivity Analysis Using a Multidimensional PEMFC Model Coupled With DAKOTA

2010 ◽  
Author(s):  
Brian Carnes ◽  
Ken S. Chen ◽  
Fangming Jiang ◽  
Gang Luo ◽  
Chao-Yang Wang
Keyword(s):  
Sensitivity Analysis ◽  
Parameter Estimation ◽  
Proton Exchange Membrane ◽  
Computational Models ◽  
Proton Exchange ◽  
Operating Conditions ◽  
Critical Parameters ◽  
Model Parameters ◽  
Two Phase ◽  
Manual Adjustment

Current computational models for proton exchange membrane fuel cells (PEMFCs) include a large number of parameters such as boundary conditions, material properties, and numerous parameters used in sub-models for membrane transport, two-phase flow and electrochemistry. In order to successfully use a computational PEMFC model in design and optimization, it is important to identify critical parameters under a wide variety of operating conditions, such as relative humidity, current load, temperature, etc. Moreover, when experimental data is available in the form of polarization curves or local distribution of current and reactant/product species (e.g., O2, H2O concentrations), critical parameters can be estimated in order to enable the model to better fit the data. Sensitivity analysis and parameter estimation are typically performed using manual adjustment of parameters, which is also common in parameter studies. We present work to demonstrate a systematic approach based on using a widely available toolkit developed at Sandia called DAKOTA that supports many kinds of design studies, such as sensitivity analysis as well as optimization and uncertainty quantification. In the present work, we couple a multidimensional PEMFC model (which is being developed, tested and later validated in a joint effort by a team from Penn State Univ. and Sandia National Laboratories) with DAKOTA through the mapping of model parameters to system responses. Using this interface, we demonstrate the efficiency of performing simple parameter studies as well as identifying critical parameters using sensitivity analysis. Finally, we show examples of optimization and parameter estimation using the automated capability in DAKOTA.

Fluid Dynamic Characterization of Operating Conditions for Continuous Flow Blood Pumps

ASAIO Journal ◽  
1999 ◽  
Vol 45 (5) ◽  
pp. 442-449 ◽  
Author(s):  
ZHONGJUN J. WU ◽  
JAMES F. ANTAKI ◽  
GREG W. BURGREEN ◽  
KENNETH C. BUTLER ◽  
DOUGLAS C. THOMAS ◽  
...  
Keyword(s):  
Continuous Flow ◽  
Fluid Dynamic ◽  
Operating Conditions ◽  
Dynamic Characterization ◽  
Blood Pumps

scholarly journals Comparison of Swine and Human Computational Hemodynamics Models for the Study of Coronary Atherosclerosis

2021 ◽  
Vol 9 ◽  
Author(s):  
Giuseppe De Nisco ◽  
Claudio Chiastra ◽  
Eline M. J. Hartman ◽  
Ayla Hoogendoorn ◽  
Joost Daemen ◽  
...  
Keyword(s):  
Coronary Arteries ◽  
Coronary Atherosclerosis ◽  
Computational Models ◽  
Fluid Dynamic ◽  
Western World ◽  
Dynamic Simulations ◽  
Anatomical Features ◽  
Coronary Syndrome ◽  
Flow Features ◽  
Long Time

Coronary atherosclerosis is a leading cause of illness and death in Western World and its mechanisms are still non completely understood. Several animal models have been used to 1) study coronary atherosclerosis natural history and 2) propose predictive tools for this disease, that is asymptomatic for a long time, aiming for a direct translation of their findings to human coronary arteries. Among them, swine models are largely used due to the observed anatomical and pathophysiological similarities to humans. However, a direct comparison between swine and human models in terms of coronary hemodynamics, known to influence atherosclerotic onset/development, is still lacking. In this context, we performed a detailed comparative analysis between swine- and human-specific computational hemodynamic models of coronary arteries. The analysis involved several near-wall and intravascular flow descriptors, previously emerged as markers of coronary atherosclerosis initiation/progression, as well as anatomical features. To do that, non-culprit coronary arteries (18 right–RCA, 18 left anterior descending–LAD, 13 left circumflex–LCX coronary artery) from patients presenting with acute coronary syndrome were imaged by intravascular ultrasound and coronary computed tomography angiography. Similarly, the three main coronary arteries of ten adult mini-pigs were also imaged (10 RCA, 10 LAD, 10 LCX). The geometries of the imaged coronary arteries were reconstructed (49 human, 30 swine), and computational fluid dynamic simulations were performed by imposing individualized boundary conditions. Overall, no relevant differences in 1) wall shear stress-based quantities, 2) intravascular hemodynamics (in terms of helical flow features), and 3) anatomical features emerged between human- and swine-specific models. The findings of this study strongly support the use of swine-specific computational models to study and characterize the hemodynamic features linked to coronary atherosclerosis, sustaining the reliability of their translation to human vascular disease.

scholarly journals Evaluation of Reaction Between 2,4-Thiazolidinedione and P-Methoxybenzaldehyde in Microreactors for Production of Drugs for Treatment of Diabetes Mellitus Type 2

2020 ◽  
Author(s):  
Rodrigo Vieira ◽  
Harrson Santana ◽  
João Silva Jr. ◽  
Paula Meira ◽  
Gabriel Bressan ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Fluid Dynamic ◽  
Batch Reactor ◽  
Biological Action ◽  
Operating Conditions ◽  
Diabetes Mellitus Type ◽  
Reaction Yield ◽  
Dynamic Simulations ◽  
Diabetes Mellitus Type Ii ◽  
Pharmaceutical Industries

The use of microreactors in chemical and pharmaceutical industries allow a series of advantages due to their reduced sizes regarding conventional batch reactors. In the present paper the transposition of the reaction between 2,4-Thiazolidinedione with p-Methoxybenzaldehyde, generating the compound with potential biological action against diabetes mellitus type II, from batch to a continuous capillary microreactor was carried out. The microdevice performance was evaluated experimentally and numerically by Computational Fluid Dynamics. The efficiency and viability of microreactors usage for the intermediate pharmaceutical active production was assessed. The optimized operating conditions were obtained for the batch reactor (processing time) and microreactor (residence time), the promoter base selection and optimal concentration was also performed, in order to maximize reactants conversion and reaction yield. Considering the acquired data, computational fluid dynamic simulations were carried out, allowing obtaining a computational methodology to be used for a fast increment of production from microreactor to industrial demand.

scholarly journals Fluid dynamic characteristics of a rotating shear stressor simulating rotary blood pumps.

2001 ◽  
Vol 13 (1) ◽  
pp. 14-18 ◽  
Author(s):  
Ahmed Aouidef ◽  
Takashi Yamane ◽  
Osamu Maruyama ◽  
Masahiro Nishida
Keyword(s):  
Dynamic Characteristics ◽  
Fluid Dynamic ◽  
Blood Pumps ◽  
Rotary Blood Pumps

scholarly journals Evaluation of Reaction Between 2,4-Thiazolidinedione and P-Methoxybenzaldehyde in Microreactors for Production of Drugs for Treatment of Diabetes Mellitus Type 2

2020 ◽  
Author(s):  
Rodrigo Vieira ◽  
Harrson Santana ◽  
João Silva Jr. ◽  
Paula Meira ◽  
Gabriel Bressan ◽  
...  
Keyword(s):  
Diabetes Mellitus ◽  
Fluid Dynamic ◽  
Batch Reactor ◽  
Biological Action ◽  
Operating Conditions ◽  
Diabetes Mellitus Type ◽  
Reaction Yield ◽  
Dynamic Simulations ◽  
Diabetes Mellitus Type Ii ◽  
Pharmaceutical Industries

The use of microreactors in chemical and pharmaceutical industries allow a series of advantages due to their reduced sizes regarding conventional batch reactors. In the present paper the transposition of the reaction between 2,4-Thiazolidinedione with p-Methoxybenzaldehyde, generating the compound with potential biological action against diabetes mellitus type II, from batch to a continuous capillary microreactor was carried out. The microdevice performance was evaluated experimentally and numerically by Computational Fluid Dynamics. The efficiency and viability of microreactors usage for the intermediate pharmaceutical active production was assessed. The optimized operating conditions were obtained for the batch reactor (processing time) and microreactor (residence time), the promoter base selection and optimal concentration was also performed, in order to maximize reactants conversion and reaction yield. Considering the acquired data, computational fluid dynamic simulations were carried out, allowing obtaining a computational methodology to be used for a fast increment of production from microreactor to industrial demand.

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