Modeling of Uncertainty Propagation for Transient Heat Rejection Problems

Generic plate and experiment-related high-fidelity models to study uncertainty propagation and transient processes for heat rejection problems are developed. The stochastic Biot numbers on the top and bottom surfaces of the plate, Bi1 and Bi2, and stochastic dimensionless input parameters, describing initial and convection boundary conditions, are introduced to define temperature variation in the modeled systems. The resulting uncertainty amplitude demonstrates a varying time evolution across a wide range of mean values of the input parameters. Depending on which input parameters are stochastic, the uncertainty may increase or decrease over time, or remain small for a given time interval in the case of the plate model. For small Bi1,2, dimensionless characteristic time for a temperature variation curve to approach its steady state is (Bi1+Bi2)-1 and large. An extremum in a temperature variation curve may appear when the Biot numbers are unequal and disappears if Bi1=Bi2. Results are nonsymmetric with respect to interchanging Bi1 and Bi2. Despite the difference in shape, the temperature variation profile over a specific region in the experimental test section numerically described by the high-fidelity model is close to the corresponding results provided by the plate model for the same Biot numbers, convection boundary, and initial conditions.

Automated summary

This study develops generic plate and experiment-related high-fidelity models to study uncertainty propagation and transient processes for heat rejection problems. The introduction of stochastic Biot numbers and stochastic dimensionless input parameters allows for the definition of temperature variation in the modeled systems. The study finds that the uncertainty amplitude varies over time depending on the mean values of the input parameters, and the results exhibit both symmetric and asymmetric characteristics. The high-fidelity model provides similar temperature variation profiles to the plate model in the experimental test section.