• wetting
• wettability
• velocity
• triple line
• spreading
• roughness
• droplet
• drop
• contact angle
• balance

This investigation, funded by CEA (Commisariat à l’Energie Atomique), has the intent to understand the behaviour of the contact angle with respect to the triple line velocity.

Three effects on this relationship have been pointed out:
- Type of the surface (Aluminium, Brass, Copper, Plexiglass and Stainless Steel),
- Flow field (inlet volumetric flow rate ranging from 0.005 ml/min up to 1 ml/min)
- Roughness (from Ra < 0.01μm up to Ra = 0.7μm).

The work has been implemented also with different momentum balances both in vertical and radial directions.
The vertical one has been already assessed for static bubbles and droplets in previous studies at DESTEC Dept.
The radial force balance is a new approach to establish if there are the conditions for the droplet to spread over the surface. It is presented here with two different approaches both leading to the same results, validated by the experiments carried out.

A further overall energy balance has been implemented and solved via experimental data. This last balance has underlined the importance of the process of interface growth as the most effective phenomenon in restraining the spreading of the droplet.