After presenting our empirical research framework (the COSMOCE Project, which focused on collaborative and synchronous design activities), we explain why knowledge dynamics is a matter of interest for understanding and modeling the product design process and rationale. The assumption is made that an argumentative situation -- typical of product design --is a good means to study knowledge dynamics in regards to the design problem (requirements definition) and the solution. A theoretical framework incorporating our point of view on the concepts of knowledge, collaborative design and argumentation is presented to justify the design experiment situation we constructed. The empirical study that was carried out is then presented with a description of the situation through the proposed task, the participants, the tools they used, the steps they took, the instructions given to them, the resources put at their disposal and the deliverables expected from them. The collected data are described and some examples are given. Finally, we describe our analyses method and present some results related to knowledge dynamics .