Experimental and numerical study on the thermal plumes of a standing and lying human in an operating room

This article presents the results of a numerical study to examine the transport of particles in an operating room equipped with an Econoclean ventilation system. Its aims are to reduce the number of particles falling onto the operating table. A simplified CFD model of the operating room was developed and validated based on the measured air velocity distribution. An SST k-ω turbulent flow model was used to simulate the airflow, while a discrete phase model was used to simulate the movement of the airborne particles. The effects of the standing posture of the surgical staff on the settlement of the particles on the operating table were examined. Results show that under the present ventilation system, when the surgical staff bend forward at an angle of 45°, the number of airborne particles that tend to fall onto the operating table increased by 1.4-fold. Adding an exhaust grille to the operating room does not have any significant effects on the distribution of the airborne particles. However, when a larger air supply diffuser is also used, the number of airborne particles that settled on the operating table was reduced 4-fold. More airborne particles are transported towards the exhaust grilles, and more airborne particles accumulate below the operating table. The present study shows that the usage of large air supply diffuser in the operating room is capable of reducing the number of airborne particles fall onto the operating table. Also, it enhances the efficiency of airborne particle removal.

Download Full-text

Numerical study of temperature-controlled airflow in comparison with turbulent mixing and laminar airflow for operating room ventilation

Building and Environment ◽

10.1016/j.buildenv.2018.08.010 ◽

2018 ◽

Vol 144 ◽

pp. 45-56 ◽

Cited By ~ 13

Author(s):

Cong Wang ◽

Sture Holmberg ◽

Sasan Sadrizadeh

Keyword(s):

Operating Room ◽

Turbulent Mixing ◽

Numerical Study ◽

Room Ventilation ◽

Temperature Controlled

Download Full-text

Does a mobile laminar airflow screen reduce bacterial contamination in the operating room? A numerical study using computational fluid dynamics technique

Patient Safety in Surgery ◽

10.1186/1754-9493-8-27 ◽

2014 ◽

Vol 8 (1) ◽

pp. 27 ◽

Cited By ~ 9

Author(s):

Sasan Sadrizadeh ◽

Ann Tammelin ◽

Peter V Nielsen ◽

Sture Holmberg

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Operating Room ◽

Bacterial Contamination ◽

Numerical Study

Download Full-text

Influence of Ceiling Height on Airflow and Particle Distribution in an Operating Room

E3S Web of Conferences ◽

10.1051/e3sconf/201911101032 ◽

2019 ◽

Vol 111 ◽

pp. 01032

Author(s):

Aleyna Agirman ◽

Yunus Emre Cetin ◽

Mete Avci ◽

Orhan Aydin

Keyword(s):

Operating Room ◽

Particle Distribution ◽

Numerical Study ◽

Surgical Site Infections ◽

Particle Dispersion ◽

Ansys Fluent ◽

Change Rate ◽

Numerical Predictions ◽

Air Change Rate ◽

Ceiling Height

Bacteria-carrying particles released by surgical staff are the main factors leading to surgical site infections (SSI). Operating rooms must be designed to reduce risks of such infections. In this numerical study, the effect of different ceiling heights on particle dispersion and deposition are studied for an operating room with laminar airflow (LAF) system. Two different particle diameters (12 and 20 ìm) are tested under three different ceiling heights (2.43–2.8–3.0 m) at a constant air change rate (ACH=20). Numerical predictions are performed by using the commercial software ANSYS Fluent 16.0. The results reveal that decreasing of the ceiling height reduces the amount of particle deposited on the surgical table.

Download Full-text

Compressible plume dynamics and stability

Journal of Fluid Mechanics ◽

10.1017/s0022112098001736 ◽

1998 ◽

Vol 369 ◽

pp. 125-149 ◽

Cited By ~ 35

Author(s):

MARK PETER RAST

Keyword(s):

Numerical Study ◽

Compressible Medium ◽

Acoustic Excitation ◽

Magnetic Field Generation ◽

Stellar Envelope ◽

Thermal Plumes ◽

Plume Region ◽

Flow Evolution ◽

Secondary Instabilities ◽

Pressure Perturbations

This paper presents a numerical study of the dynamics and stability of two-dimensional thermal plumes in a significantly stratified layer. Motivated by stellar envelope convection in which radiative cooling at the star's photosphere drives vigorous down flows, we examine cool plumes descending through an adiabatically stratified layer of increasing density with depth. Such flows are inaccessible by laboratory experiments, yet are important to the understanding of heat and momentum transport, magnetic field generation, and acoustic excitation in stars like the Sun. We find that the structure of thermal plumes in a stratified compressible medium is significantly different from that in an incompressible one, with pressure perturbations playing an important dynamical role. Additionally, we find that the plumes are subject to vigorous secondary instabilities even in a quiescent background medium. While the flows studied are not fully turbulent but transitional, the nature of the compressive instabilities and their influence on subsequent flow evolution suggests that advective detrainment of fluid from the plume region results. Simplified plume models assuming a hydrostatic pressure distribution and velocity-proportional entrainment may thus be inappropriate in this context.

Download Full-text

THE NUMERICAL STUDY WITH DYNAMIC MESH ON THE POLLUTION CONTROL EFFECT OF OPERATING TABLE PROTECTED BY LAMINAR FLOW SCREEN

International Journal of Modern Physics Conference Series ◽

10.1142/s2010194516601563 ◽

2016 ◽

Vol 42 ◽

pp. 1660156

Author(s):

JULI FAN ◽

LU TIAN ◽

XUDONG JIA

Keyword(s):

Numerical Simulation ◽

Laminar Flow ◽

Operating Room ◽

Pollution Control ◽

Numerical Study ◽

Dynamic Mesh ◽

Operating Table ◽

Discrete Phase Model ◽

Three Dimensional Model ◽

Control Effect

Transmission of airborne bacteria is the main factor causing surgical site infection (SSI). Horizontal laminar flow screen is a kind of new clean equipment, which can prevent SSI effectively. Numerical simulation is conducted on the pollution control effect of operating table protected by horizontal laminar flow screen. A three-dimensional model is established, discrete phase model (DPM) is used for calculation. Numerical simulation is carried out to evaluate the particle trajectories with the Lagrange approach, and the dynamic mesh is used. Air movement in the case with and without people’s walking is analyzed. As a result, people’s walking would not affect the distribution of pollutants at the key area of the operating table, the vertex caused by the walking person does little influence on flow field of the whole operating room and the influence area is about 0.24m to 0.75m around the walking person. The protective effect of pollutants with horizontal laminar flow screen for the key areas of operating table is excellent. This work provides references for the study on the depuration of operating room or other occasion.

Download Full-text

Effect of a circulating nurse walking on airflow and bacteria-carrying particles in the operating room: An experimental and numerical study

Building and Environment ◽

10.1016/j.buildenv.2020.107315 ◽

2020 ◽

Vol 186 ◽

pp. 107315

Author(s):

Zhijian Liu ◽

Haiyang Liu ◽

Rui Rong ◽

Guoqing Cao

Keyword(s):

Operating Room ◽

Numerical Study

Download Full-text

Convective heat transfer along ratchet surfaces in vertical natural convection

Journal of Fluid Mechanics ◽

10.1017/jfm.2019.446 ◽

2019 ◽

Vol 873 ◽

pp. 1055-1071 ◽

Cited By ~ 1

Author(s):

Hechuan Jiang ◽

Xiaojue Zhu ◽

Varghese Mathai ◽

Xianjun Yang ◽

Roberto Verzicco ◽

...

Keyword(s):

Heat Transfer ◽

Natural Convection ◽

Convective Heat Transfer ◽

Heat Transport ◽

Convective Heat ◽

Large Scale ◽

Numerical Study ◽

Thermal Plumes ◽

Transport Efficiency ◽

Convection Roll

We report on a combined experimental and numerical study of convective heat transfer along ratchet surfaces in vertical natural convection (VC). Due to the asymmetry of the convection system caused by the asymmetric ratchet-like wall roughness, two distinct states exist, with markedly different orientations of the large-scale circulation roll (LSCR) and different heat transport efficiencies. Statistical analysis shows that the heat transport efficiency depends on the strength of the LSCR. When a large-scale wind flows along the ratchets in the direction of their smaller slopes, the convection roll is stronger and the heat transport is larger than the case in which the large-scale wind is directed towards the steeper slope side of the ratchets. Further analysis of the time-averaged temperature profiles indicates that the stronger LSCR in the former case triggers the formation of a secondary vortex inside the roughness cavity, which promotes fluid mixing and results in a higher heat transport efficiency. Remarkably, this result differs from classical Rayleigh–Bénard convection (RBC) with asymmetric ratchets (Jiang et al., Phys. Rev. Lett., vol. 120, 2018, 044501), wherein the heat transfer is stronger when the large-scale wind faces the steeper side of the ratchets. We reveal that the reason for the reversed trend for VC as compared to RBC is that the flow is less turbulent in VC at the same $Ra$. Thus, in VC the heat transport is driven primarily by the coherent LSCR, while in RBC the ejected thermal plumes aided by gravity are the essential carrier of heat. The present work provides opportunities for control of heat transport in engineering and geophysical flows.

Download Full-text