Transpiration through hydrogels

Hydrogels are hydrophylic polymer networks that can absorb many times their own weight in water. A common example is the gel that is included in disposable nappies but types of hydrogel are also found in the stoma of leaves and in the xylem of trees. These latter examples are involved in the transport of water upwards through trees, so-called transpiration. The aim is to develop and solve mathematical models that incorporate and quantify the dynamics of hydrogels in situations in which water is passing through them. For example, water-saturated hydrogel with one surface exposed to unsaturated air and another surface immersed in water will cause water to pass through it. This flow is not driven by external pressures but by gradients in internally generated osmotic pressures.