The Weissenberg number (Wi) is a dimensionless number used in the study of viscoelastic flows. It is named after Karl Weissenberg. The dimensionless number compares the elastic forces to the viscous forces. It can be variously defined, but it is usually given by the relation of stress relaxation time of the fluid and a specific process time. For instance, in simple steady shear, the Weissenberg number, often abbreviated as Wi or We, is defined as the shear rate {\displaystyle {\dot {\gamma }}}{\displaystyle {\dot {\gamma }}} times the relaxation time {\displaystyle \lambda }\lambda . Using the Maxwell model and the Oldroyd-B model, the elastic forces can be written as the first Normal force (N1).

全新#OPEN wi.de 官配整车来了
#搭配ENVE碳纤维系列

NEW: AXS + ENVE COMPLETE WI.DE. !

We have been asked many times if we can upgrade our best-selling WI.DE. SRAM Force/Eagle complete bike with carbon wheels. Now we can! We have a new complete bike coming with full ENVE Composites specifications and the legendary SRAM Mullet drivetrain!#gravelbike#

Dear Open partner, 亲爱的OPEN伙伴
a couple of good news:两个好消息跟你们分享一下：

1: 新的棕色wi.de车架首批限量50台即日开放预定！
We got a new colour for the WIDE. The Classic brown is back. Right now only 50 units worldwide. No idea when we get the next ones but i have my doubt for this year.

2: 新的灰色min.d限量40台即日接受预定！
We got a limited batch of MIND in the grey/orange matt design same as the UP. One batch 40 units will never come again...#gravelbike#