In this paper n, k are natural numbers, X is a non empty set, and S is a σ-field of subsets of X. Next we state several propositions: (1) Let M be a σ-measure on S, F be a function from N into S, and given n. Then {x ∈ X: ∧ k (n ≤ k ⇒ x ∈ F (k))} is an element of S. (2) Let F be a sequence of subsets of X and n be an element of N. Then (the superior set sequence of F )(n) = ⋃ rng(F ↑ n) and (th...

ABSTRCT: Use CFD method to study of the air distribution of certain practical project. By using three-dimensional RNG k-εturbulent model, the air distribution of an underground main workshop in hydropower station with heat source at non-isothermal condition has been designed by means of numerical simulation. Solve the controlling equations by using the soft ware of computational fluid dynamics ...

For simplicity, we adopt the following rules: X denotes a non empty set, F denotes a sequence of partial functions from X into R with the same dom, s1, s2, s3 denote sequences of extended reals, x denotes an element of X, a, r denote extended real numbers, and n, m, k denote natural numbers. We now state several propositions: (1) If for every natural number n holds s2(n) ≤ s3(n), then inf rng s...

Most indoor airflows are mixed convection. In order to simulate mixed convection accurately and efficiently, this paper uses a two-layer turbulence model. The two-layer model combines a one-equation model for near wall flow together with the standard k-epsilon model for outer-wall flow. The model has been used to predict the mixed convection by displacement ventilation in an office. The compute...

In this study, the thermal characteristics of turbulent nanofluid flow in a helical tube in the tube heat exchanger (HTTHE) were assessed numerically through computational fluid dynamics (CFD) simulation. The findings of both the turbulent models: realizable k-epsion (k-ε) and re-normalisation group (RNG) k-epsilon were compared. The temperature distribution contours show that realizable and RN...