# Pressure drop for viscous fluid in conducts with an obstacle at the outlet

1. Feb 22, 2012

### pippobaudo

Hello,

I have the following system (see enclosed figure): A viscous (non newtonian) fluid at high temperature is going trough a tube at a known mass flow, at the exit there is an inclined plane at a given angle (b).
I would like to estimate in some way how the inclined plane at the exit influences the Pressure drop between the entrance and the tube exit. In addition i'd like to calculate how the pressure drop varies as a function of the angle (b) of the inclined plane.

Any help is appreciated, also If you could suggest some good books on viscous flow hydrodynamics.

Thanks guys,
Pippo

2. Feb 22, 2012

### Andy Resnick

I don't understand why you (apparently) equate viscosity with non-Newtonian behavior.

Your figure is not attached, but the behavior of a viscous fluid leaving a constricted tube (a nozzle) is fairly straightforward in most cases. Streeter's "Fluid Mechanics" is a decent place to start.

3. Feb 23, 2012

### pippobaudo

Hello and thanks for the reply,

well let's say that is a very viscous fluid which, in order to be fluidized, has to be heated to more than 100 Celsius.
I try to enclose again the figure, (I go to "manage Attachments" and upload) I hope It will be attached this time.

Best regards,

#### Attached Files:

• ###### B_L_figure.gif
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4. Feb 23, 2012

### Andy Resnick

Ok, so the viscosity is a (strong) function of temperature. I wonder if that is more important than whatever nozzle geometry you have- what is the temperature of the fluid as it travels down the pipe and impinges on the plate? If the temperature becomes nonuniform (say the plate is cold but the fluid is hot), I would think the dominant effect would be due to the changes in viscosity.

5. Feb 24, 2012

### pippobaudo

Hi, yes I think you are right, the temperature for fluidizing the medium is 120 Celsius.
However now I'd like to solve the problem assuming uniform viscosity, laminar flow and steady state conditions. In addition the temperature of the tube walls including the external object is assumed equal to that of the fluid.

I am thinking about finding the drag coefficient for this particular geometry and then estimate the force done on the flat surface, from this force will be possible to estimate (in some way....) a back pressure on the fluid so that the pressure drop between the entrance and tube exit will be estimated.

I didnt find yet this geometry among the drag coefficients for immersed bodies...
Thanks

6. Feb 24, 2012