TY - JOUR JF - mdrsjrns JO - Modares Mechanical Engineering VL - 15 IS - 5 PY - 2015 Y1 - 2015/7/01 TI - Uncertainty Quantification of RANS Turbulence Models for Power-law Non-Newtonian Fluid Flows TT - کمی‌سازی عدم قطعیت مدل‌های آشفتگی RANS برای جریان سیال غیرنیوتنی توانی N2 - Non-Newtonian fluid flows experience turbulent regime in some industrial applications. Several approaches have been proposed for numerical simulation of turbulent flows that each one has specific features. RANS turbulence models have reasonable computational costs, while include several sources of uncertainties affecting simulation results. In addition, developed RANS models for non-Newtonian fluids are modified versions of available models for Newtonian fluids, therefore, they cannot provide reliable estimation for viscoplastic stress term. On the contrary, DNS delivers accurate results but with high computational costs. Consequently, use of DNS data for estimation of uncertainty in RANS models can provide better decision making for engineers based on RANS results. In the present study, a turbulence model based on for power-law non-Newtonian fluid is developed and employed for simulation of flow in a pipe. Then, an efficient method is proposed for quantification of available model-form uncertainty. Moreover, it is assumed that uncertainties originating from various sources are combined together in calculation of Reynolds stress as well as viscoplastic stress. Deviation of the stresses, computed using RANS turbulence model, from DNS data are modeled through Gaussian Random Field. Thereafter, Karhunen-Loeve expansion is employed for uncertainty propagation in simulation process. Finally, the effects of these uncertainties on RANS results are shown in velocity field demonstrating the fact that the presented approach is accurate enough for statistical modeling of model-form uncertainty in RANS turbulence models. SP - 287 EP - 294 AU - Esfahanian, Vahid AU - Rahbari, Iman AU - Mortazavi, Mohammad Hossein AD - KW - Turbulence Modeling KW - non-Newtonian fluid KW - uncertainty quantification KW - Direct Numerical Simulation KW - Karhunen-Loeve Expansion UR - http://mme.modares.ac.ir/article-15-11556-en.html ER -