Feigley Charles E, Bennett James S, Khan Jamil, Lee Eungyoung
Department of Environmental Health Sciences, HESC, Room 311, School of Public Health, University of South Carolina, Columbia, SC 29208, USA.
AIHA J (Fairfax, Va). 2002 Jul-Aug;63(4):402-12. doi: 10.1080/15428110208984728.
Contaminant concentration estimates from simple models were compared with concentration fields obtained by computational fluid dynamic (CFD) simulations for various room and source configurations under steady-state conditions. Airflow and contaminant distributions in a 10 x 3 x 7-m room with a single contaminant source on a 1-m high table were simulated using CFD for steady, isothermal conditions. For a high wall jet inlet, simulations were performed for nine room air exhaust locations and eight source locations. For a ceiling diffuser inlet the impact of two exhaust locations and eight source locations were investigated. Because CFD treats determinants of contaminant transport explicitly and agreed well with experimental results, it was used as the standard for comparison. Parameters of the one- and two-zone completely mixed models (CM-1 and CM-2) and the uniform turbulent diffusivity model (UD) were determined from CFD simulation results. Concentration estimates from these were compared with CFD results in the breathing zone (BZ) plane (1.5 m above the floor) for the entire BZ, the source "near field," and the source "far field." In the near field the mean percentage difference between the model concentration estimates and the CFD results for all room configurations were -21.9, 32.3, and 126% for the CM-1, CM-2, and UD models, respectively, with standard deviations of 26.8, 111, and 103%. In the far field the mean percentage difference between the model estimates and CFD results were -4.8, -2.3, and -36.3%. The CM-1 model had generally the best performance for applications such as occupational epidemiology for the conditions and configurations studied. However, CM-1 tended to underestimate the near field concentration; thus, CM-2 was judged to be better in the near field when underestimation is undesirable, such as when determining compliance with occupational exposure limits. The agreement of CM-2 estimates with CFD results in the near field was more variable than that of the CM-1. The UD model performed poorly on average in both near and far fields, and the difficulty in accurately estimating the turbulent diffusivity presents a significant impediment to UD model use for exposure estimation.
在稳态条件下，将简单模型得出的污染物浓度估算值与通过计算流体动力学（CFD）模拟得到的各种房间和污染源配置下的浓度场进行了比较。使用CFD对一个10×3×7米的房间进行了气流和污染物分布模拟，该房间内有一个位于1米高桌子上的单一污染物源，模拟条件为稳态、等温。对于高壁面射流入口，针对九个房间排气位置和八个污染源位置进行了模拟。对于天花板散流器入口，研究了两个排气位置和八个污染源位置的影响。由于CFD明确处理了污染物传输的决定因素且与实验结果吻合良好，因此将其用作比较标准。单区和两区完全混合模型（CM - 1和CM - 2）以及均匀湍流扩散模型（UD）的参数由CFD模拟结果确定。将这些模型得出的浓度估算值与CFD在呼吸区（BZ）平面（地面上方1.5米）整个区域、污染源“近场”和污染源“远场”的结果进行了比较。在近场中，对于所有房间配置，CM - 1、CM - 2和UD模型的模型浓度估算值与CFD结果之间的平均百分比差异分别为 - 21.9%、32.3%和126%，标准差分别为26.8%、111%和103%。在远场中，模型估算值与CFD结果之间的平均百分比差异分别为 - 4.8%、 - 2.3%和 - 36.3%。对于所研究的条件和配置，CM - 1模型在职业流行病学等应用中总体表现最佳。然而，CM - 1往往低估近场浓度；因此，当不希望出现低估情况时，例如在确定是否符合职业接触限值时，CM - 2在近场中被认为更好。CM - 2估算值与CFD在近场结果的一致性比CM - 1更具变异性。UD模型在近场和远场的平均表现都很差，并且准确估算湍流扩散率的困难对UD模型用于暴露估算构成了重大障碍。
