An improved composite element method for the simulation of temperature field in massive concrete with embedded cooling pipe

Computational effort is intensive and usually reduced at the cost of accuracy in the simulation of temperature field in massive concrete with embedded cooling pipe. In this investigation, an improved composite element method (CEM) was proposed to improve the computational efficiency without sacrificing the accuracy. The region surrounding cooling pipe is differentiated into three sub-regions according to their local temperature gradient and material constituent. Three sub-elements are used to represent these sub-regions in a composite element. Dynamical degradation of composite element to finite element avoids the refining of mesh in the areas surrounding cooling pipe. Therefore, computational efficiency is significantly improved. The size of the sub-region with sharp local temperature gradient is optimized to achieve better accuracy. Variation of the cooling water temperature along the pipe was taken into consideration to further improve the accuracy of the proposed method. Good agreement of the results using proposed method with finite element method (FEM) confirms its validity. (C) 2017 Elsevier Ltd. All rights reserved.