sometimes the need for non-circular ducts arises in many heat transfer applications because of lower pressure drop of non-circular cross section such as square duct compared to circular tube, particularly in compact heat. but square cross section has poor heat transfer performance and it is expected that using a nanofluid as a new heat transfer media may improve the heat transfer performance of...

Article history: Received 19 February 2008 Accepted 16 April 2008 Available online 7 July 2008

In the author's PhD thesis (2019) universal envelopes were introduced as a tool for studying continuously obtainable information on discontinuous functions. To any function $f \colon X \to Y$ between $\operatorname{qcb}_0$-spaces one can assign so-called envelope which, in well-defined sense, encodes all function. A consists of two continuous functions $F L$ and $\xi_L Y with values $\Sigma$-sp...