A diffuse interface method for the Navier–Stokes/Darcy equations: Perfusion profile for a patient-specific human liver based on MRI scans

2017 ◽  
Vol 321 ◽  
pp. 70-102 ◽  
Author(s):  
Stein K.F. Stoter ◽  
Peter Müller ◽  
Luca Cicalese ◽  
Massimiliano Tuveri ◽  
Dominik Schillinger ◽  
...  
Keyword(s):  
Human Liver ◽  
Diffuse Interface ◽  
Navier Stokes ◽  
Patient Specific ◽  
Mri Scans ◽  
Darcy Equations

scholarly journals Numerical computation of blood flow for a patient-specific hemodialysis shunt model

2021 ◽  
Author(s):  
Surabhi Rathore ◽  
Tomoki Uda ◽  
Viet Q. H. Huynh ◽  
Hiroshi Suito ◽  
Toshitaka Watanabe ◽  
...  
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Arteriovenous Shunt ◽  
Navier Stokes ◽  
Patient Specific ◽  
Stabilized Finite Element ◽  
Computed Tomography Scanning ◽  
Outflow Boundary ◽  
Stage Renal Disease ◽  
End Stage

AbstractHemodialysis procedure is usually advisable for end-stage renal disease patients. This study is aimed at computational investigation of hemodynamical characteristics in three-dimensional arteriovenous shunt for hemodialysis, for which computed tomography scanning and phase-contrast magnetic resonance imaging are used. Several hemodynamical characteristics are presented and discussed depending on the patient-specific morphology and flow conditions including regurgitating flow from the distal artery caused by the construction of the arteriovenous shunt. A simple backflow prevention technique at an outflow boundary is presented, with stabilized finite element approaches for incompressible Navier–Stokes equations.

scholarly journals A model order reduction approach to create patient-specific mechanical models of human liver in computational medicine applications

2019 ◽  
Vol 170 ◽  
pp. 95-106 ◽  
Author(s):  
Nathan Lauzeral ◽  
Domenico Borzacchiello ◽  
Michael Kugler ◽  
Daniel George ◽  
Yves Rémond ◽  
...  
Keyword(s):  
Human Liver ◽  
Model Order Reduction ◽  
Order Reduction ◽  
Patient Specific ◽  
Model Order ◽  
Mechanical Models ◽  
Reduction Approach

scholarly journals Towards integration of 64Cu-DOTA-trastuzumab PET-CT and MRI with mathematical modeling to predict response to neoadjuvant therapy in HER2 + breast cancer

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Angela M. Jarrett ◽  
David A. Hormuth ◽  
Vikram Adhikarla ◽  
Prativa Sahoo ◽  
Daniel Abler ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Targeted Therapy ◽  
Treatment Response ◽  
Growth Factor Receptor ◽  
Patient Specific ◽  
Mathematical Framework ◽  
Breast Cancer Patients ◽  
Data Types ◽  
Her2 Breast Cancer ◽  
Mri Scans

AbstractWhile targeted therapies exist for human epidermal growth factor receptor 2 positive (HER2 +) breast cancer, HER2 + patients do not always respond to therapy. We present the results of utilizing a biophysical mathematical model to predict tumor response for two HER2 + breast cancer patients treated with the same therapeutic regimen but who achieved different treatment outcomes. Quantitative data from magnetic resonance imaging (MRI) and 64Cu-DOTA-trastuzumab positron emission tomography (PET) are used to estimate tumor density, perfusion, and distribution of HER2-targeted antibodies for each individual patient. MRI and PET data are collected prior to therapy, and follow-up MRI scans are acquired at a midpoint in therapy. Given these data types, we align the data sets to a common image space to enable model calibration. Once the model is parameterized with these data, we forecast treatment response with and without HER2-targeted therapy. By incorporating targeted therapy into the model, the resulting predictions are able to distinguish between the two different patient responses, increasing the difference in tumor volume change between the two patients by > 40%. This work provides a proof-of-concept strategy for processing and integrating PET and MRI modalities into a predictive, clinical-mathematical framework to provide patient-specific predictions of HER2 + treatment response.

Predicting critical closing pressure in children with obstructive sleep apnea using fluid structure interaction simulations

2021 ◽  
Author(s):  
Goutham Mylavarapu ◽  
Ephraim Gutmark ◽  
Sally Shott ◽  
Robert J. Fleck ◽  
Mohamed Mahmoud ◽  
...  
Keyword(s):  
Obstructive Sleep Apnea ◽  
Sleep Apnea ◽  
Upper Airway ◽  
Dynamic Mri ◽  
Patient Specific ◽  
Apnea Hypopnea Index ◽  
Structure Interaction ◽  
Obstructive Sleep ◽  
Mri Scans ◽  
Closing Pressure

Surgical treatment of obstructive sleep apnea (OSA) in children requires knowledge of upper airway dynamics, including the closing pressure (Pcrit), a measure of airway collapsibility. We applied a Flow-Structure Interaction (FSI) computational model to estimate Pcrit in patient-specific upper airway models obtained from magnetic resonance imaging (MRI) scans. We sought to examine the agreement between measured and estimated Pcrit from FSI models in children with Down syndrome. We hypothesized that the estimated Pcrit would accurately reflect measured Pcrit during sleep and therefore reflect the severity of OSA as measured by the obstructive apnea hypopnea index (AHI). All participants (n=41) underwent polysomnography and sedated sleep MRI scans. We used Bland Altman Plots to examine the agreement between measured and estimated Pcrit. We determined associations between estimated Pcrit and OSA severity, as measured by AHI, using regression models. The agreement between passive and estimated Pcrit showed a fixed bias of -1.31 (CI=-2.78, 0.15) and a non-significant proportional bias. A weaker agreement with active Pcrit was observed. A model including AHI, gender, an interaction term for AHI and gender and neck circumference explained the largest variation (R2 = 0.61) in the relationship between AHI and estimated Pcrit. (P <0.0001). Overlap between the areas of the airway with lowest stiffness, and areas of collapse on dynamic MRI, was 77.4%±30% for the nasopharyngeal region and 78.6%±33% for the retroglossal region. The agreement between measured and estimated Pcrit and the significant association with AHI supports the validity of Pcrit estimates from the FSI model.

Application of Interface-Tracking Method Based on Phase-Field Model to Numerical Analysis of Isothermal and Thermal Two-Phase Flows

2007 ◽  
Author(s):  
Naoki Takada
Keyword(s):  
Phase Field ◽  
Density Ratio ◽  
Phase Field Model ◽  
Field Method ◽  
Diffuse Interface ◽  
Phase Field Method ◽  
Navier Stokes ◽  
Interface Tracking ◽  
Two Phase Flows ◽  
Two Phase

For interface-tracking simulation of two-phase flows in various micro-fluidics devices, the applicability of two versions of Navier-Stokes phase-field method (NS-PFM) was examined, combining NS equations for a continuous fluid with a diffuse-interface model based on the van der Waals-Cahn-Hilliard free-energy theory. Through the numerical simulations, the following major findings were obtained: (1) The first version of NS-PFM gives good predictions of interfacial shapes and motions in an incompressible, isothermal two-phase fluid with high density ratio on solid surface with heterogeneous wettability. (2) The second version successfully captures liquid-vapor motions with heat and mass transfer across interfaces in phase change of a non-ideal fluid around the critical point.

Kinetics of fiber impregnation by a binder. Gradient generalization of Navier–Stokes–Darcy equations

2016 ◽  
Vol 9 (2) ◽  
pp. 205-208 ◽  
Author(s):  
P. A. Belov ◽  
A. S. Borodulin ◽  
L. P. Kobets ◽  
G. V. Malysheva
Keyword(s):  
Navier Stokes ◽  
Darcy Equations ◽  
Kinetics Of

CFD Analysis of Wind Loads on Permeable Low-Rise Structures

2012 ◽  
Vol 152-154 ◽  
pp. 1814-1820
Author(s):  
Isam Janajreh
Keyword(s):  
Cross Sections ◽  
Degrees Of Freedom ◽  
Stokes Equations ◽  
Experimental Studies ◽  
Wind Load ◽  
Navier Stokes ◽  
Euler Beam ◽  
Clemson University ◽  
Viscous Shear ◽  
Darcy Equations

Current screen enclosure building codes are based on the experimental wind tunnel studies and, to a smaller extent, full scale open terrain studies conducted at Virginia Tech and Clemson University. There are still widespread wind damages to pool and patio enclosures during wind storms. Experimental studies based on simulation comparison of wind load on a low-rise structure in general, continue to show large discrepancies based on NIST data. Accounting for the many parameters which are essential to achieve an accurate simulation through experimentation is daunting. Reynolds number, spectrum density, large and small turbulent scales, viscous shear layer, and flow intermittency are a few of those parameters. Numerical simulation (CFD) provides an attractive parametric study and offers a richer, higher resolution data output. In this work, flow around a screen enclosure embedded within the atmospheric boundary layer is investigated numerically. The flow is governed by Navier-Stokes equations with a momentum sink that follows Darcy equations and incorporating the eddy viscosity k-ε turbulent closure model. The pressure drop that is computed provides the basis of evaluating wind load on the screen structure. The evaluated load is compared to the Florida Building Code ASCE7 provision and is used to conduct structural analysis on common baseline enclosures to assess their reliability. The structure is analyzed using Bernoulli-Euler beam elements having cross sections according to the code and subjected to forces and moments with 6 (3displacements and 3 rotational) degrees of freedom.

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