# Viscosity, two immicible phase flow, wettabilility

• I
• Jabbar_B
In summary, the conversation discusses the behavior of two immiscible fluids, a wetting phase (water) and a non-wetting phase (oil), on an inclined surface. It is mentioned that in the case of a single wetting phase, the closest layer to the surface will be bounded and the velocity of flow will be inversely proportional to the viscosity of the fluid. However, when a second non-wetting phase is introduced, it will flow on top of the wetting phase, with its velocity dependent on viscosity. The conversation also mentions the existence of studies on the friction between immiscible fluids in flow conditions.
Jabbar_B
If the single phase flows on the inclined surface and this phase (let's say water) is wetting the surface then closest layer to the surface will be bounded and will not move. And velocity of flow will be in inverse proportion with viscosity of the fluid.
If now the second phase is introduced, immicible and non-wetting phase (lets say oil), it flow on top of the wetting phase. So non-wetting phase will flow on top of the thin film of wetting phase which is bounded to the surface. So now, would velocity of the non-wetting phase be dependent on the Viscosity similarly as in single wetting phase case?
J

Yes. It would be dependent on the viscosity.

non-wetting fluid (oil) flows on top of the wetting fluid (water film on top of the surface). And because these two fluids do not mix that mean oil is "ice skate" on top of the water. In that case velocity will not merely depend on viscosity unlike the case when oil is wetting the surface and outer most layer is attached to surface.

is there any study on friction between immiscible fluids in flow condition?

J

Jabbar_B said:
non-wetting fluid (oil) flows on top of the wetting fluid (water film on top of the surface). And because these two fluids do not mix that mean oil is "ice skate" on top of the water. In that case velocity will not merely depend on viscosity unlike the case when oil is wetting the surface and outer most layer is attached to surface.

is there any study on friction between immiscible fluids in flow condition?

J

There are entire books on the subject. You are asking for the jump momentum balance condition across the deformable boundary, first written out by Scriven in 1960:

http://www.sciencedirect.com/science/article/pii/0009250960870030

Bird, Stewart, and Lightfoot, Transport Phenomena, solve the problem of two fluids in contact with one another of different viscosities flowing through a flow channel. Across the interface, the shear stress and normal stress are continuous.

Chestermiller said:
Bird, Stewart, and Lightfoot, Transport Phenomena, solve the problem of two fluids in contact with one another of different viscosities flowing through a flow channel. Across the interface, the shear stress and normal stress are continuous.

They don't have to be continuous- the interface may be separately modeled (Boussinesq surface fluid) with properties distinct from bulk phases. Similarly, the Laplace equation ΔP=2σκ is a jump condition across a deformed interface.

Andy Resnick said:
They don't have to be continuous- the interface may be separately modeled (Boussinesq surface fluid) with properties distinct from bulk phases. Similarly, the Laplace equation ΔP=2σκ is a jump condition across a deformed interface.
Good point. Thanks.

## 1. What is viscosity?

Viscosity is the measure of a fluid's resistance to flow. It is a property that describes the internal friction of a fluid and is affected by factors such as temperature and pressure.

## 2. How is viscosity measured?

Viscosity is typically measured using a viscometer, which is a device that measures the time it takes for a fluid to flow through a specific tube or opening. The longer the time, the higher the viscosity.

## 3. What is two immiscible phase flow?

Two immiscible phase flow refers to the movement of two different fluids that do not mix or dissolve in each other, such as oil and water. This type of flow is often seen in oil extraction and water pollution remediation processes.

## 4. How does wettability affect fluid flow?

Wettability refers to the ability of a fluid to spread and adhere to a solid surface. In the context of fluid flow, wettability can affect the movement of fluids through porous media, such as in oil reservoirs. A fluid with high wettability will have a better ability to flow through the pores and extract oil from the reservoir.

## 5. What factors affect wettability?

Wettability can be affected by factors such as surface tension, contact angle, and the chemical composition of the fluid and solid surfaces. Changes in these factors can alter the wettability and ultimately impact the flow behavior of the fluid.

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