A Computational Study of a Passive Flow Device in a Mechanical Heart Valve for the Anatomic Aorta and the Axisymmetric Aorta

The purpose of this research is to present a warm air infiltration simulation for a cold room, considering the effects of an air curtain. At present, there exist a large number of retail businesses, operating within an industry entailing high investment and competition. Therefore, retail operators must distinguish factors that are essential to lowering their costs, one of which is energy reduction. A survey of energy consumption in stores found that most used energy is due to the cooling system. Therefore, we tested the protection of cold rooms against air inflow by conducting three simulations: 1. Without an air curtain; 2. using an air curtain having a common grille; and 3. using an air curtain with a honeycomb grille. The cold room temperature was set to 1 °C, the cold room door was 200 × 100 m2, and the air curtain was installed 5 cm above the cold room door; furthermore, the velocity of air emitted from the air curtain was 6.5 m/s. Warm air infiltration simulations were carried out using SolidWorks Flow Simulation software, in order to determine the temperature change in the cold room and the airflow direction. From the results of the comparative experiments, when using the different wind grilles, there were differences in the infiltration of warm air. The honeycomb grille reduced air turbulence in the cold room more effectively than the common grille. As a result, the temperature in the cold room was consistent, and the temperature inside the cold room was maintained 10.62% lower when using a honeycomb grille compared to a common grille.

Section: Mesh Independencementioning

confidence: 99%

Investigation and Analysis of Air Curtains for the Improvement of Refrigeration Energy Efficiency

Pongsupat

Taweekun

Saengsikhiao

2022

“…Each wave profile was presented against the number of cycles within the first 10 cycles, Figure 12 shows that each wave required 4 cycles to be stable. This result will be used later in irregular wave simulation to spot the real action of sea wave spectrum [21].…”

Section: Stability Of the Generated Wavementioning

confidence: 99%

CFD Modeling of Regular and Irregular Waves Generated by Flap Type Wave Maker

Eldeen

El-Baz

Elmarhomy

2021

The improvement of wave generation in numerical tanks represents the key factor in ocean engineering development to save time and effort in research concerned with wave energy conversion. For this purpose, this paper introduces a numerical simulation method to generate both regular and irregular waves using Flap-Type wave maker. A 2D numerical wave tank model is constructed with a numerical beach technique, the independence of the numerical beach slope is tested to reduce the wave reflections. The different governing parameters of the Flap type wave maker were studied such as periodic time dependency and length of the flap stroke. The linear wave generated was validated against the wave maker theory WMT, the numerical results agreed with WMT. The Pierson-Moskowitz model is used to generate irregular waves with different frequencies and amplitudes. The numerical model succeeded to generate irregular waves which was validated against published experimental data and with Pierson-Moskowitz spectrum model using Fourier expansion theory in the frequency domain. Useful results are presented in this paper based on the numerical simulation to understand the characteristics of the waves. This paper produces a full guide to generate both regular and irregular waves numerically using ANSYS-CFX approach to solve the 2D Unsteady Reynolds Averaged Navier-Stokes Equation (URANS).

“…The non-physiological flow pattern around MHV is caused by its mechanical leaflet geometry, implantation direction and angle. Those are important causes of artificial heart valve dysfunction, higher wall shear stress formed on the aortic [19], which can cause severe hemodynamic damage and some complications from the growth of abnormal tissues around the MHV.…”

Section: Introductionmentioning

confidence: 99%

Numerical Study of Subaortic Stenosis and Pannus Formation on Blood Flow Around Mechanical Heart Valves

Aolin Chen,

Adi Azriff Basri,

Norzian Ismail

et al. 2022

Patients after mechanical heart valve implantation are prone to complications. Mechanical heart valve obstruction is a rare but life-threatening complication. Obstruction may include thrombosis, pannus formation around the valve, or both. However, the relationship between thrombus and pannus and mechanical heart valve hemodynamics has not been thoroughly studied. We studied the fluid dynamics of thrombus and pannus formation through numerical simulations and provided detailed information about the interaction between complications and related prosthetic valves so that complications can be detected early. Studies have shown that the formation of thrombus and pannus leads to significant changes in the peak transvalvular velocity of the artificial valve, the transvalvular pressure gradient, and the corresponding hemodynamic indicators. As the height of the thrombus and pannus increases, the jet velocity and transvalvular pressure gradient will increase accordingly. When obstruction exceeds 20%, the impact increases significantly under the same percentage of obstacles. When the obstruction percentage is over 30%, the rest at least doubled. The results also indicate that SAS obstruction has the most significant impact on the blood flow of MHV. At the same time, it should be noted that when SAS and pannus are combined, the ring form vortex in front of the pannus has a potential risk of accelerating the deterioration of the pannus.