AIM: To investigate the flow and mixing at the duodenal stump after gastric resection, a computersimulation was implemented.METHODS: Using the finite element method, two different Billroth ? procedure cases (A and B) were modeled. Case A was defined with a shorter and almost straight duodenal section, while case B has a much longer and curved duodenal section. Velocity,pressure and food concentration distribution were determined and the numerical results were compared with experimental observations.RESULTS: The pressure distribution obtained by numerical simulation was in the range of the recorded experimental results. Case A had a more favorable pressure distribution in comparison with case B.However, case B had better performance in terms of food transport because of more continual fooddistribution,as well as better emptying of the duodenal section.