Simulation of Pulsed Water Cooling for Continuous Casting with LS-DYNA

Water cooling is a critical feature of a continuous casting process. To efficiently control the water flow at the beginning of the process without limiting the amount of water towards the end of the casting, pulsed water cooling can be used. The modelling of the pulsed water cooling is an important feature for a correct simulation of a continuous casting process. A mathematical formulation by means of Fourier series of order N has been developed and implemented in a Ls-Dyna model which allows for the modelling of steadily decreasing pulsed water cooling processes. Water cooling is described through the heat transfer coefficient (HTC) in the contact options. To represent (pulsed) water cooling conditions the HTC is described via parameters like water flow rate, the pulse rate, its period, the temperatures of both water and billet and on the timeline during casting. Ls-Dyna already is capable of modelling a dependency of the temperature and the timeline. For all other dependencies there were two possibilities within the present FE model. The first option was to define the dependencies within a *DEFINE_FUNCTION while the second option was to establish a user-defined subroutine for the calculation of the HTC. The more efficient possibility was the user-defined subroutine, which was promising to reduce the calculation time and to allow an easier definition within the keyword input file for the end-user. This paper describes the necessary steps for modelling pulsed water cooling within an implicit Ls-Dyna simulation. Additionally the impact of the different types of cooling (i.e. continuous, pulse ratio 1, pulse ratio 2) on a small scale model will be shown.