Computational fluid dynamics (CFD) simulation analysis on retinal gas cover rates using computational eye models

Abstract

We investigated the change in the retinal gas cover rates due to intraocular gas volume and positions using computational eye models and demonstrated the appropriate position after pars plana vitrectomy (PPV) with gas tamponade for rhegmatogenous retinal detachments (RRDs). Computational fluid dynamic (CFD) software was used to calculate the retinal wall wettability of a computational pseudophakic eye models using fluid analysis. The model utilized different gas volumes from 10 to 90%, in increments of 10% to the vitreous cavity in the supine, sitting, lateral, prone with closed eyes, and prone positions. Then, the gas cover rates of the retina were measured in each quadrant. When breaks are limited to the inferior retina anterior to the equator or multiple breaks are observed in two or more quadrants anterior to the equator, supine position maintained 100% gas cover rates in all breaks for the longest duration compared with other positions. When breaks are limited to either superior, nasal, or temporal retina, sitting, lower temporal, and lower nasal position were maintained at 100% gas cover rates for the longest duration, respectively. Our results may contribute to better surgical outcomes of RRDs and a reduction in the duration of the postoperative prone position.

Application of moving particle semi-implicit (MPS) method on retro-oil fluid using three-dimensional vitreous cavity models from magnetic resonance imaging

“…Although the traditional mesh-based method is easy to perform when the analysis domain has a simple shape 16 – 21 , meshing for irregular or complex shapes like the vitreous cavities of myopic eyes requires substantial manpower and mesh-collapsing issues may occur. In contrast, in the MPS method used here, the fluid itself is modeled as particles without a grid to represent space.…”

“…Next, we separated the 3-D vitreous cavity at 1:30, 4:30, 7:30, and 10:30 into four quadrants and then defined the position of the ora serrata of the inferior retina as the anatomical differences as 6.7 mm posterior to the limbus. Then, we defined the equator as 6.5 mm posterior to the ora serrata in the inferior retinal area, according to the vortex vein ampullae 15 , 16 . Therefore, the inferior quadrant of the retina was separated into two parts, inferior-anterior and inferior-posterior (Fig.…”

“…Angunawela et al reported intraocular fluid shear stresses on the retinal wall using CFD software 5 . Previously, we reported the appropriate postoperative positions after pars plana vitrectomy (PPV) with gas tamponade for RRDs using CFD software and the traditional mesh-based method 8 . Although the mesh-based method is easy to perform if the analysis domain has a simple shape, such as the spherical domain used in previous reports, many steps are required to create the mesh if the domain has an irregular or complex shape, and the calculations sometimes terminate abnormally.…”

Numerical investigation of the effect of the opening mode on the pressure relief process of engine nacelle

“…Therefore, a pressure relief door (PRD) must be installed on a nacelle that opens after the internal pressure of the nacelle increases to a certain threshold, which will maintain the internal pressure in the core casing of a high-bypass turbofan engine under a safe level to avoid structural damage or failure of the nacelle structure. In recent years, civil aviation engines have developed in the direction of a high bypass ratio and overall pressure ratio, and the fan pressure ratio has gradually decreased 2 , 3 . Compared with aircraft from the 1950s, the operating pressure and temperature of modern aircraft engines are higher, which has led to a significant increase in emissions from the nacelle pressure relief system: after the engine bleed air duct is ruptured, the nacelle structure will bear a higher pressure load, which in turn, will result in higher requirements for the discharge performance of the PRD 4 , 5 .…”

Employing computational fluid dynamics technique for analyzing the PACK-1300XY with methanol and isopropanol mixture

“…Among the numerical studies for the fluid flow throughout the packings, computational fluid dynamic (CFD) is an efficient method to reduce the economic expense of experimental measurements 29 – 32 . Moreover, another benefit of this computational method is the capability of estimation for the effect of diverse factors 33 – 35 .…”