Variation profile of contact angle with height

[thermcool]

Does anyone know how does the contact angle varies with the height inside a capillary tube or porous material. Is the variation linear or somehow logarithmic. To explain my question further, for the rise of fluid inside a capillary tube the contact angle depends upon the velocity of flow. In the start the velocity is high so contact angle is small but it changes as the velocity keep decreasing.

Thanks