Tech Briefs

New Frontiers

With the very wide use of ADINA at present, we are sometimes pleasantly surprised seeing, by chance, a paper focusing on a very interesting study conducted with ADINA! In this News we present some interesting biomechanics-related applications in which the multiphysics capabilities are used:

Sleep Apnea

In this study, the obstructive sleep apnea syndrome was considered. This is a sleep-related breathing disorder characterized by repetitive pharyngeal collapse and reopening in the oral and nasal cavity. A full 3D finite element model of the airway, skull, neck, hyoid and soft tissues surrounding the upper airway was used based on CT data of a patient. The second figure shows the finite element model where different materials are depicted with different colors. Using this finite element model, a transient fluid-structure interaction analysis was performed to study the mechanism of the collapse of pharyngeal during inspiration, which is believed to be responsible for this syndrome.

Respiration Simulation of Human Upper Airway for Analysis of Obstructive Sleep Apnea Syndrome
Renhan Huang* and Qiguo Rong*
LSMS/ICSEE 2010, LNBI 6330, pp. 588-596, 2010
*College of Engineering, Peking University, Beijing 100871, China

Cerebrospinal Flow

In this study, based on MRI images of a human subject, a 3D finite element model of the cerebrospinal fluid flow inside the central nervous system was developed. The interaction between the cerebrospinal fluid flow and the deformation of the brain tissues during the flow cycles was studied. The results were found to be in excellent agreement with the experimental data. Understanding the mechanism of cerebrospinal flow is an important step for designing drug delivery methods to the central nervous system.

Cerebrospinal Fluid Flow Dynamics in the Central Nervous System
Brian Sweetman* and Andreas A. Linninger*
Annals of Biomedical Engineering, DOI: 10.1007/s10439-010-0141-0 (2010)
*Laboratory for Product and Process Design (LPPD), Department of Bioengineering, University of Illinois at Chicago, Science and Engineering Offices (SEO), Room 218 (M/C 063), 851 S Morgan St., Chicago, IL 60607-7052, USA

For a similar study, see here.

Carotid Atheroma Rupture

Atherosclerosis at the carotid bifurcation is a major risk factor for stroke. This study presented a comparison between carotid atheroma rupture observed in vivo and the plaque stress distribution obtained from a fluid-structure interaction analysis based on pre-rupture medical imaging. A good correlation was found between the region of pronounced elevation in stress within the fibrous plaque layer of the lesion, and the location and extent of the observed site of plaque rupture.

Carotid Atheroma Rupture Observed In Vivo and FSI-Predicted Stress Distribution Based on Pre-rupture Imaging
J.R. Leach^1,2,3,  V.L. Rayz², B. Soares², M. Wintermark², M.R.K. Mofrad¹, and D. Saloner^1,2
Annals of Biomedical Engineering, DOI: 10.1007/s10439-010-0004-8, 2010
¹UC Berkeley/UC San Francisco Joint Graduate Group in Bioengineering, Berkeley, CA, USA
²Department of Radiology, Biomedical Imaging, University of California San Francisco Medical Center, San Francisco, CA, USA
³Department of Radiology, San Francisco Veterans Affairs Medical Center, San Francisco, CA, USA

For a similar study, see here.

Hovering Insect Flight

The aerodynamic characteristics of hovering flight of the Coleopteran beetle (species with flexible hind wings and stiff fore wings) was investigated. The flapping wing kinematics of the Coleopteran insect was modeled through experimental observations using high-speed digital camera photography. The kinematic data was used in the fluid-structure interaction analysis of the flapping wings during the hovering flight. The motivation of this study is to design small biomimetic flying devices, the so-called micro air vehicles.

Numerical investigation of the aerodynamic characteristics of a hovering Coleopteran insect
Tuyen Quang Le¹, Doyoung Byun¹, Saputra¹, Jin Hwan Ko¹, Hoon Choel Park², Minjun Kim³
Journal of Theoretical Biology, 266:485–495, 2010
¹Department of Aerospace and Information Engineering, Konkuk University, Seoul, Republic of Korea
²Department of Advanced Technology Fusion, Konkuk University, Seoul, Republic of Korea
³Department of Mechanical Engineering, Drexel University, Philadelphia, PA, USA

For a similar study, see here.

3D MR Flow in Thoracic Aorta

The knowledge of local vascular anatomy and function in the human body is of great interest for the diagnosis and treatment of cardiovascular disease. A comprehensive analysis of the hemodynamics in the thoracic aorta is presented based on the integration of flow-sensitive 4D MRI with state-of-the-art rapid prototyping technology and computational fluid dynamics (CFD). Rapid prototyping was used to transform aortic geometries as measured by contrast-enhanced MR angiography into realistic vascular models with large anatomical coverage. Integration into a flow circuit with patient-specific pulsatile in-flow conditions and application of flow-sensitive 4D MRI permitted detailed analysis of local and global 3D flow dynamics in a realistic vascular geometry. The results indicate the potential of such patient-specific model systems for detailed experimental simulation of realistic vascular hemodynamics.

3D MR Flow Analysis in Realistic Rapid-Prototyping Model Systems of the Thoracic Aorta: Comparison with In Vivo Data and Computational Fluid Dynamics in Identical Vessel Geometries
C. Canstein¹, P. Cachot², A. Faust², A.F. Stalder¹, J. Bock¹, A. Frydrychowicz¹, J. Küffer², J. Hennig¹, and M. Markl¹
Magnetic Resonance in Medicine, 59:535–546, 2008
¹Department of Diagnostic Radiology, Medical Physics, University Hospital, Freiburg, Germany
²Institute for Product and Production engineering, University of Applied Sciences Northwestern Switzerland, Muttenz, Switzerland

Cerebral Aneurysm

Cerebral aneurysms are pathologic dilations of an artery, generally found in the anterior and posterior regions of the circle of Willis. Rupture of a cerebral aneurysm causes subarachnoid hemorrhage with potentially severe neurologic complications. Hemodynamics plays an important role in the progression and rupture of cerebral aneurysms. This study describes the blood flow dynamics and fluid–structure interaction in seven patient-specific models of bifurcating cerebral aneurysms located in the anterior and posterior circulation regions of the circle of Willis. The models were obtained from 3D rotational angiography image data, and blood flow dynamics and fluid–structure interaction were studied under physiologically representative waveform of inflow. The arterial wall was assumed to be elastic, isotropic and homogeneous. The flow was assumed to be laminar, non-Newtonian and incompressible.

Blood flow dynamics and fluid–structure interaction in patient-specific bifurcating cerebral aneurysms
Alvaro Valencia¹, Darren Ledermann¹, Rodrigo Rivera², Eduardo Bravo² and Marcelo Galvez²
Int. J. Numer. Meth. Fluids, 58:1081–1100, 2008
¹Department of Mechanical Engineering, Universidad de Chile, Casilla 2777, Santiago, Chile
²Neuroradiology Department, Instituto de Neurocirugia Asenjo, Jose Manuel Infante 553, Santiago, Chile

You can search through more than 700 publications with reference to the use of ADINA on our Publications page.

Keywords:
Multiphysics, fluid-structure interaction, FSI, computational fluid dynamics, CFD, hemodynamics, patient specific, rapid prototyping, drug delivery, CT, MRI, angiography, sleep apnea, cerebrospinal flow, carotid atheroma rupture, Coleopteran, hovering flight, biomimetic, thoracic aorta, cerebral aneurysm