An　experimental　rotary　damper　device　with　a　corrugated　disc　and　a　plate　disc　(called　corrugated　damper)　has　been　examined.　The　narrow　gap　between　the　two　discs　is　filled　with　an　electrorheological　fluid　(or　magnetorheological　suspension);　therefore,　the　electrostructural　effect　has　to　be　taken　into　consideration.　Computational　fluid　dynamics　(FLUENT　software)　is　used　to　produce　comparative　performance　data　between　corrugated　rotary　damper　and　ordinary　dual-plate　rotary　damper.　Theoretical　and　numerical　studies　have　shown　that　the　total　output　torque　increment　for　the　corrugated　disc　rotary　damper　is　significantly　larger　than　that　of　the　dual-disc　rotary　damper　when　the　impact　of　the　electric　field　strength　is　ignored.　The　results　help　the　optimal　design　of　a　pre-prototyping　structure　with　an　electrorheological　(or　magnetorheological　suspension)　fluid　damper.