Analysis of drag effects on pulsatile blood flow in a right coronary artery by using Eulerian multiphase model

Yilmaz, Fuat,Kutlar, Ahmet Ihsan,Gundogdu, Mehmet Yasar 한국유변학회 2011 Korea-Australia rheology journal Vol.23 No.2

The influence of the presence of neighboring entities on drag in blood flow where the dominating mechanisms are expected to be viscous, drag, and gravity forces is investigated in a 3-D anatomically realistic right coronary artery. A classical Eulerian multiphase model on the Fluent v6.3.26 platform is used to model pulsatile non-Newtonian blood flow. Two new drag models based on the mixture viscosity concept are developed by using the drag similarity criteria. In literature, drag models based on the mixture viscosity concept are only depended on volume fraction and show Newtonian viscosity effects on drag. However, mixture viscosity depends on the primary independent variables such as the volume fraction and the shear rate in most of the dispersed flows like blood flow. Non-Newtonian drag effects on red blood cell are so calculated by using these new volume fraction and the shear rate dependent drag models. Five different drag models including these new drag models are used to model the blood flow in this study to investigate the effectiveness of drag force model on blood flow.

Analysis of conventional drag and lift models for multiphase CFD modeling of blood flow

Yilmaz, Fuat,Gundogdu, Mehmet Yasar The Korean Society of Rheology 2009 Korea-Australia rheology journal Vol.21 No.3

This study analyzes especially drag and lift models recently developed for fluid-solid, fluid-fluid or liquid-liquid two-phase flows to understand their applicability on the computational fluid dynamics, CFD modeling of pulsatile blood flow. Virtual mass effect and the effect of red blood cells, RBCs aggregation on CFD modeling of blood flow are also shortly reviewed to recognize future tendencies in this field. Recent studies on two-phase flows are found as very useful to develop more powerful drag-lift models that reflect the effects of blood cell's shape, deformation, concentration, and aggregation.

A critical review on blood flow in large arteries; relevance to blood rheology, viscosity models, and physiologic conditions

Yilmaz, Fuat,Gundogdu, Mehmet Yasar The Korean Society of Rheology 2008 Korea-Australia rheology journal Vol.20 No.4

The purpose of this study is mainly directed towards present of viewpoints on critical and commentary analysis on blood rheology, blood viscosity models, and physiological flow conditions. Understanding these basics is fundamental to meet the need for a sufficient and reliable CFD model of blood. Most of the used viscosity models on this manner have determined from parameter fitting on experimental viscosity data. Availability of experimental data from literature to define viscosity models of CFD analysis should be accurately chosen and treated in order to avoid any errors. Several basic gaps that limit the CFD model results are identified and given opportunities for future research.

Analysis of conventional drag and lift models for multiphase CFD modeling of blood flow

Fuat Yilmaz,Mehmet Yasar Gundogdu 한국유변학회 2009 Korea-Australia rheology journal Vol.21 No.3

This study analyzes especially drag and lift models recently developed for fluid-solid, fluid-fluid or liquidliquid two-phase flows to understand their applicability on the computational fluid dynamics, CFD modeling of pulsatile blood flow. Virtual mass effect and the effect of red blood cells, RBCs aggregation on CFD modeling of blood flow are also shortly reviewed to recognize future tendencies in this field. Recent studies on two-phase flows are found as very useful to develop more powerful drag-lift models that reflect the effects of blood cell’s shape,deformation, concentration, and aggregation.

A critical review on blood flow in large arteries; relevance to blood rheology, viscosity models, and physiologic conditions

Fuat Yilmaz,Mehmet Yasar Gundogdu 한국유변학회 2008 Korea-Australia rheology journal Vol.20 No.4

The purpose of this study is mainly directed towards present of viewpoints on critical and commentary analysis on blood rheology, blood viscosity models, and physiological flow conditions. Understanding these basics is fundamental to meet the need for a sufficient and reliable CFD model of blood. Most of the used viscosity models on this manner have determined from parameter fitting on experimental viscosity data. Availability of experimental data from literature to define viscosity models of CFD analysis should be accurately chosen and treated in order to avoid any errors. Several basic gaps that limit the CFD model results are identified and given opportunities for future research.

Analysis of drag effects on pulsatile blood flow in a right coronary artery by using Eulerian multiphase model

Fuat Yilmaz,Ahmet Ihsan Kutlar,Mehmet Yasar Gundogdu 한국유변학회 2011 Korea-Australia rheology journal Vol.23 No.2

The influence of the presence of neighboring entities on drag in blood flow where the dominating mechanisms are expected to be viscous, drag, and gravity forces is investigated in a 3-D anatomically realistic right coronary artery. A classical Eulerian multiphase model on the Fluent v6.3.26 platform is used to model pulsatile non-Newtonian blood flow. Two new drag models based on the mixture viscosity concept are developed by using the drag similarity criteria. In literature, drag models based on the mixture viscosity concept are only depended on volume fraction and show Newtonian viscosity effects on drag. However, mixture viscosity depends on the primary independent variables such as the volume fraction and the shear rate in most of the dispersed flows like blood flow. Non-Newtonian drag effects on red blood cell are so calculated by using these new volume fraction and the shear rate dependent drag models. Five different drag models including these new drag models are used to model the blood flow in this study to investigate the effectiveness of drag force model on blood flow.

Elevated Neutrophil-to-Lymphocyte Ratio in Squamous Cell Carcinoma of Larynx Compared to Benign and Precancerous Laryngeal Lesions

Kum, Rauf Oguzhan,Ozcan, Muge,Baklaci, Deniz,Kum, Nurcan Yurtsever,Yilmaz, Yavuz Fuat,Gungor, Volkan,Unal, Adnan Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.17

Background: Laryngeal carcinogenesis is a multifactorial process that has not been fully elucidated. Despite extensive research, reliable markers with diagnostic and prognostic value are still lacking. It was recently reported that an elevated preoperative neutrophil-to-lymphocyte ratio (NLR) may correlate with an increased risk of recurrence, tumor aggressiveness and poorer prognosis in various malignancies. The aim of this study was to examine whether NLR could be used as an inflammatory marker to differentiate laryngeal squamous cell carcinoma (LSCC) patients from benign laryngeal lesion (BLL) and precancerous laryngeal lesion (PLL) patients. Materials and Methods: This retrospective study was performed on 209 patients admitted to a tertiary referral center with laryngeal lesions and undergoing biopsies to establish their histopathological diagnosis. We reviewed the patient files for their clinical, histopathological and laboratory data. The patients were divided into three groups according to their histopathological findings, as BLL, PLL and LSCC groups. The patients in the PLL group were also divided into three subgroups as mild, moderate and severe dysplasia/carcinoma in situ (CIS) subgroups. The groups were compared for NLR and the other laboratory data. Results: The mean NLRs of the BLL, PLL and the LSCC groups were $2.12{\pm}0.86$, $2.32{\pm}0.68$ and $3.46{\pm}1.51$, respectively, and the difference was statistically significant (p=0.001). The mean NLRs of the patients with PLL and LSCC were significantly higher than the patients with BLL (p=0.031 and p=0.001, respectively). The mean NLRs were similar among mild dysplasia, moderate dysplasia and severe dysplasia / CIS groups (p>0.05). Conclusions: To our knowledge, this is the first study investigating NLR in BLL, PLL and LSCC. NLR is an inexpensive, reproducible and widely available blood test, and could be a useful inflammatory marker to differentiate LSCC from BLL and PLL.