Large Eddy Simulations of Flow Around a Cylinder with Uncertain Wall Heating

Numerical simulations of the turbulent flow and heat transfer around an array of cylinder are carried out at Reynolds number ReD = 3, 900. The wall heat flux is assumed to be uncertain and characterized by highest variance in the stagnation point region. Simulations are carried out using a novel uncertainty propagation scheme, the hybrid stochastic projection method. This technique combines the accuracy and convergence properties of intrusive stochastic Galerkin methods with the non-intrusive nature of stochastic collocation. Reynolds averaged and Large Eddy simulations are used to estimate the variability induced by the uncertain boundary conditions; the comparison between the two approaches provides an indirect estimate of the epistemic uncertainty associated to the simplification introduced by the turbulence modeling. The sensitivity of the predictions to the assumed wall heating variability is also presented and shows that the expectation and variance of the temperature converge more slowly when LES is considered.