Learning Forum

[schwehr]

🛈 This post originally contained file attachments which have been removed in compliance with the updated Ansys Learning Forum Terms & Conditions

Sehr geehrte Damen und Herrn,

 

für die Bearbeitung eines Studienprojektes soll mittels ANSYS Discovery Live eine Strömungssimulation von Wasserstrahldüsen durchgeführt werden.

 

Bei der angefügten Datei handelt es sich um die in der Abbildung dargestellte stark vereinfachte Düse.

Die Simulationsergebnisse mittels ANSYS Discovery Live weisen eine nicht zu vernachlässigende Abweichung der Austrittsgeschwindigkeit von 12,5% über der analytischen Berechnung mittels ideeller Bernoulligleichung auf.

 

Bezüglich des Ergebnisses stellen sich mir folgende Fragen:

-Sind bei dem Simulationsergebnis bereits Reibungswerte miteinbezogen? 

-Ist die beigefügte Simulationsdatei falsch aufgebaut?

-Gibt es Möglichkeiten durch Anpassung am Modell die Simulationsergebnisse zu verbessern?

-Wie sind die auftretenden Diskrepanzen(da das Simulationsergebnis über den Ergebnissen der ideellen verlustfreien Bernoulligleichung liegt) zu begründen?

 

Mit freundlichen Grüßen 

Alexander Schwehr

Hochschule Ulm

SYM

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English translation:
 

Dear Ladies and Gentlemen,

 

For the processing of a study project, a flow simulation of water jet nozzles is to be carried out using ANSYS Discovery Live.

 

The attached file is the greatly simplified nozzle shown in the figure.

The simulation results using ANSYS Discovery Live show a non-negligible deviation of the exit velocity of 12.5% above the analytical calculation using the ideal Bernoulli equation.

 

Regarding the result, I ask myself the following questions:

- Are friction values already included in the simulation result? 

-Is the attached simulation file incorrectly structured?

-Is there any possibility to improve the simulation results by adapting the model?

-How are the discrepancies that arise (since the simulation result is above the results of the ideal lossless Bernoulli equation)?

 

With best regards 

Alexander Schwehr

Ulm University of Applied Sciences

SYM

[Naresh Patre]

Hello Alexander Schwehr

Are you comparing the maximum velocity or the average velocity at the outlet from Discovery Live with the hand calculation? I think if you compare the latter one, the difference might be less that 10%.

While using Discovery Live, it should be noted that results from Discovery Live are not intended to be compared with other results for its accuracy. The instantaneous simulation results should be used to understand the trends in results based on changes in the geometry and/or input conditions. And from these trends you can quickly identify the best design on which you can perform a high fidelity simulation.

I would also like to mention here that Discovery Live is now replaced with Discovery which provides a common interface for modeling, performing instantaneous simulation as well as high fidelity simulation. You can check out the videos on Discovery from the Tutorials section available on the home page of this forum.

[schwehr]

Hello Naresh 

Compared is the maximum velocity at the outlet. 

Using the average velocity leads to a better result.

According to your advice I consider to switch to Discovery.

thank you for your explanations and fast response.