An online tool based on computational fluid dynamics modelling was developed, validated and applied to Colakoglu Metallurji 2-strands slab caster to monitor and manage steel intermixing in tundish at ladle change. The tool allows to reduce the length of the slabs with intermixed steel. Different tundish layout and operating conditions are accounted for as slab size, presence of flow modifiers in tundish, tundish refill time, casting speed (also different from strand to strand), steel grade. The tool was developed by CSM following the suggestions and needs of Colakoglu Metallurji, who provided to a successful validation of such tool, both with slab sampling and support for installation and testing. As a result, the tool has been integrated into the Colakoglu CC2 control system and is currently used offline for optimizing a priori mixed grade production scheduling, and online for slab cutting optimization in order to reduce the downgraded product amount.