A　mathematical　model　for　a　bladder-urethra　system　can　provide　basic　analysis　for　the　disabled　urethra　closure　of　stress　urinary　incontinence　(SUI)　patients　in　a　clinic.　Based　on　computational　fluid　dynamics　(CFD),　we　developed　a　three-dimensional　urodynamic　bladder-urethra　system,　which　includes　bladder,　bladder　neck,　prostate,　and　urethra.　The　realistic　recirculation　process　of　the　urinary　bladder　during　the　physiologic　voiding　process　in　conjunction　with　a　flow　simulation　through　the　female　urinary　bladder　and　urethra　is　presented.　The　computational　results　show　that　a　dead-water　zone　and　the　zone　of　secondary　flow　occur,　independent　of　the　shape　of　the　prostatic　urethra.　For　the　pathological　prostata,　the　extreme　constriction　of　the　prostatic　urethra　results　in　an　additional　wide-stretched　dead-water　zone.　The　simulation　results　does　not　only　improve　urinary　incontinence　surgery　for　clinicians,　but　can　also　provide　a　basis　for　theoretical　analysis.　©　2010　Higher　Education　Press　and　Springer-Verlag　Berlin　Heidelberg.