It is known that the longitudinal vortex alternately and periodically forms diagonally backward of the upstream cylinder of the cruciform system consisted of the upstream cylinder and the downstream strip-plate and causes the strong periodic lift force on the upstream cylinder. We have had a new concept to form a longitudinal vortex steadily at a fixed position. in where the gap betwe... https://hollandscountryclothinges.shop/product-category/zip-neck-sweaters/