A blood flow with cardiac pulse in intracranial aneurysms using computational fluid dynamics (CFD): A comparison between transient and steady state regimes

2017 ◽  
Vol 17 (4) ◽  
pp. 873-885
Author(s):  
Alejandro Acevedo-Malavé
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Steady State ◽  
Intracranial Aneurysms ◽  
Computational Fluid Dynamics Cfd ◽  
Cardiac Pulse ◽  
Transient And Steady State

CFD Leakage Predictions of Unworn and Worn Labyrinth Seals With and Without Tooth Axial Offset

2017 ◽  
Author(s):  
Hasham H. Chougule ◽  
Alexander Mirzamoghadam
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Numerical Modeling ◽  
Steady State ◽  
Flow Field ◽  
Labyrinth Seals ◽  
Small Clearance ◽  
Total Leakage ◽  
Computational Fluid Dynamics Cfd ◽  
Flow Deflection

The objective of this study is to develop a Computational Fluid Dynamics (CFD) based methodology for analyzing and predicting leakage of worn or rub-intended labyrinth seals during operation. The simulations include intended tooth axial offset and numerical modeling of the flow field. The purpose is to predict total leakage through the seal when an axial tooth offset is provided after the intended/unintended rub. Results indicate that as expected, the leakage for the in-line worn land case (i.e. tooth under rub) is higher compared to unworn. Furthermore, the intended rotor/teeth forward axial offset/shift with respect to the rubbed land reduces the seal leakage. The overall leakage of a rubbed seal with axial tooth offset is observed to be considerably reduced, and it can become even less than a small clearance seal designed not to rub. The reduced leakage during steady state is due to a targeted smaller running gap because of tooth offset under the intended/worn land groove shape, higher blockages, higher turbulence and flow deflection as compared to worn seal model without axial tooth offset.

Computational Fluid Dynamics (CFD) Study of the 4th Generation Prototype of a Continuous Flow Ventricular Assist Device (VAD)

2004 ◽  
Vol 126 (2) ◽  
pp. 180-187 ◽  
Author(s):  
Xinwei Song ◽  
Houston G. Wood ◽  
Don Olsen
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Ventricular Assist Device ◽  
Continuous Flow ◽  
Surrounding Tissue ◽  
Assist Device ◽  
Ventricular Assist ◽  
Wide Range ◽  
Computational Fluid Dynamics Cfd

The continuous flow ventricular assist device (VAD) is a miniature centrifugal pump, fully suspended by magnetic bearings, which is being developed for implantation in humans. The CF4 model is the first actual prototype of the final design product. The overall performances of blood flow in CF4 have been simulated using computational fluid dynamics (CFD) software: CFX, which is commercially available from ANSYS Inc. The flow regions modeled in CF4 include the inlet elbow, the five-blade impeller, the clearance gap below the impeller, and the exit volute. According to different needs from patients, a wide range of flow rates and revolutions per minute (RPM) have been studied. The flow rate-pressure curves are given. The streamlines in the flow field are drawn to detect stagnation points and vortices that could lead to thrombosis. The stress is calculated in the fluid field to estimate potential hemolysis. The stress is elevated to the decreased size of the blood flow paths through the smaller pump, but is still within the safe range. The thermal study on the pump, the blood and the surrounding tissue shows the temperature rise due to magnetoelectric heat sources and thermal dissipation is insignificant. CFD simulation proved valuable to demonstrate and to improve the performance of fluid flow in the design of a small size pump.

Numerical Simulations of the Non-Newtonian Blood Blow in Human Abdominal Artery Based on Reverse Engineering

2011 ◽  
Vol 140 ◽  
pp. 195-199 ◽  
Author(s):  
Jin You YANG ◽  
Yang Hong
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Fluid Flow ◽  
Reverse Engineering ◽  
Power Law ◽  
Cardiac Cycle ◽  
Hemodynamic Parameters ◽  
Human Artery ◽  
Computational Fluid Dynamics Cfd

The method that combined the reverse engineering based on CT medical images and computational fluid dynamics (CFD) was used to perform simulation the Non-Newtonian blood fluid flow in human abdominal artery, then analyzed the hemodynamic condition about the bifurcation of human abdominal artery. A Non-Newtonian blood model (the Generalised Power Law) was used to study the hemodynamic parameters during entire cardiac cycle. Calculated results for the Non-Newtonian blood flow show us the methods performed in this study is suitable for numerical simulating the blood flow in human artery and investigating the relation between hemodynamic factors and vascular disease.

Microfabricated Cavities for Adhesive Capture of Stem Cells Under Flow

2007 ◽  
Author(s):  
Dooyoung Lee ◽  
Kuldeepsinh Rana ◽  
Karin Lee ◽  
Lisa A. DeLouise ◽  
Michael R. King
Keyword(s):  
Fluid Dynamics ◽  
Stem Cells ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Shear Stresses ◽  
Computational Fluid Dynamics Cfd ◽  
Future Work ◽  
Flow Experiments

In previous work, we have described the adhesive capture of circulating stem cells to surfaces coated with adhesive selectin protein, both in vitro and in vivo. Here we describe PDMS surfaces microfabricated to contain an array of square 80 × 80 × 80 micron cavities. These cavities are intended to provide a local bioreactor environment to culture stem cells over extended periods of time, while sheltered from the higher shear stresses of the surrounding blood flow external of the cavities. In this paper we present in vitro flow experiments with polymeric, blood cell-sized microspheres, showing the creation of stable vortices within the microscale cavities. Computational fluid dynamics (CFD) was performed to predict the velocity field within the cavity, and for comparison with experimentally determined microsphere velocities. Future work will establish the ability to place local chemoattract molecules within the cavity interior, and the ability to accumulate viable stem cells within these cavities.

Hemodynamic Phenotypes of Anatomically Realistic Terminal Aneurysms

2008 ◽  
Author(s):  
Matthew D. Ford ◽  
Sang-Wook Lee ◽  
Marina Piccinelli ◽  
Luca Antiga ◽  
David A. Steinman
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Life Cycle ◽  
Surgical Procedures ◽  
Intracranial Aneurysms ◽  
Unruptured Aneurysm ◽  
Cfd Simulations ◽  
Hemodynamic Forces ◽  
Determining Factors ◽  
Computational Fluid Dynamics Cfd

Intracranial aneurysms occur in approximately 4% of the population. While advances in medical imaging and surgical procedures have led to improved diagnosis and treatment, the decision of whether or not too treat an unruptured aneurysm is still largely subjective. The size of the aneurysm combined with its location and shape are the major determining factors, along with experience, when considering treatment. There is increasing recognition that hemodynamic forces play a key role in the life cycle of an aneurysm; however, it is difficult to provide this information in the clinic, owing to the need for time-consuming computational fluid dynamics (CFD) simulations. A more pragmatic solution, for now at least, may be to predict the gross flow patterns (“hemodynamic phenotype”) from simpler-to-measure geometric parameters.

Three-Dimensional CFD Analysis of Gas Mixing in Large Volumes

2001 ◽  
Author(s):  
Brian L. Smith
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Steady State ◽  
Three Dimensional ◽  
Air Injection ◽  
Cfd Analysis ◽  
Gas Mixing ◽  
Air Mixing ◽  
Computational Fluid Dynamics Cfd ◽  
Pure Steam

Abstract The paper describes three-dimensional Computational Fluid Dynamics (CFD) calculations undertaken in support of analyses of steam/air mixing which takes place in the drywell volumes of the 1/40th-scale ESBWR1 mock-up facility PANDA under conditions of symmetric steam/air injection and asymmetric outflow. Steady-state simulations for pure steam conditions illustrate how the flow streams mix to ensure balanced outflow conditions to the condensers. A transient calculation has also been performed to examine how air released from solution in the PANDA boiler would ultimately accumulate in the separate condenser units. Results provide a possible explanation for the rundown in performance of one of the condensers which was repeatedly observed in some of the PANDA tests.

Achieving high parallel performance for an unstructured unsteady turbomachinery CFD code

2007 ◽  
Vol 111 (1117) ◽  
pp. 185-193 ◽  
Author(s):  
N. Hills
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Steady State ◽  
Load Balancing ◽  
Unstructured Mesh ◽  
Test Cases ◽  
Hexahedral Mesh ◽  
Parallel Performance ◽  
Computational Fluid Dynamics Cfd ◽  
Work Done

This paper describes the work done to achieve high parallel performance for an unstructured, unsteady turbomachinery computational fluid dynamics (CFD) code. The aim of the work described here is to be able to scale problems to the thousands of processors that current and future machine architectures will provide. The CFD code is in design use in industry and is also used as a research tool at a number of universities. High parallel scalability has been achieved for a range of turbomachinery test cases, from steady-state hexahedral mesh cases to fully unsteady unstructured mesh cases. This has been achieved by a combination of code modification and consideration of the parallel partitioning strategy and resulting load balancing. A sliding plane option is necessary to run fully unsteady multistage turbomachinery test cases and this has been implemented within the CFD code. Sample CFD calculations of a full turbine including parts of the internal air system are presented.

Validation of an Open Source Framework for the Simulation of Blood Flow in Rigid and Deformable Vessels

2013 ◽  
Author(s):  
T. Passerini ◽  
A. Quaini ◽  
U. Villa ◽  
A. Veneziani ◽  
S. Canic
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Numerical Methods ◽  
Open Source ◽  
Open Source Framework ◽  
Computational Fluid Dynamics Cfd ◽  
Scientific Endeavor ◽  
The Right ◽  
Computational Analyses

Computational methods are the tool of choice for the study of physics phenomena in many fields of scientific endeavor. To guarantee the reliability of the results of computational analyses, it is crucial that mathematical models are validated and numerical methods are verified. A verified method is capable of correctly solving the problem equations, while a valid model is able to correctly describe the features of the problem (i.e. it uses the right equations). In this paper we: (i) verify and validate an open source computational fluid dynamics (CFD) framework for the solution of problems of interest in hemodynamics and (ii) provide a report on the methodology that we use, to make our experiences reproducible.

An Immersed Porous Boundary Method for Computational Fluid Dynamics of Blood Flow in Aneurysms With Flow Diverters

2012 ◽  
Author(s):  
Viorel Mihalef ◽  
Puneet Sharma ◽  
Ali Kamen ◽  
Thomas Redel
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Blood Flow ◽  
Subarachnoid Hemorrhage ◽  
Cerebral Artery ◽  
Intracranial Aneurysms ◽  
Mortality Rates ◽  
Morbidity And Mortality ◽  
High Morbidity ◽  
Flow Diverters

Intracranial aneurysms are pathological dilatations of a cerebral artery that may suffer rupture and lead to subarachnoid hemorrhage. Such a condition presents high morbidity and mortality rates for the patients concerned.

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