September 21, 2018 at 9:10 ammichele rocchiSubscriber
I would like to clarify a doubt that I have regarding reaction in a multiphase domain.
Considering a domain where a disperse phase is present, and a reaction ongoing only in the continuous phase (a variable composition mixture)
Given the rate of consumption or production of a species per unit volume, when inserting the expression in the fluid source of the subdomain used to model the reaction, should the value be multiplied by the local volume fraction of the phase in which the reaction occur?
In other word given the value "r" [kg/m^3/s] and the element volume in the domain "v" [m^3] and the volume fraction of the continuous phase "a" [vol/vol] is CFX calculating the consumption or the production of a specie as "dmi/dt" [kg/s] as dmi/dt=r*v or dmi/dt=a*r*v?
September 22, 2018 at 9:46 pmKarthik RAdministrator
Since this is a CFX question, I am moving this to the 'Fluid Dynamics' thread so it gets better traction.
September 23, 2018 at 5:02 amraul.raghavSubscriberSince the reaction occurs only on the continuous phase, you can define the continuity source term using the Fluid Source tab inside the subdomain. If you created the subdomain based on the entire domain, select the “Total Fluid Mass Source” in the continuity source term definition and assign “r” as its value. The volume “v” of the subdomain will be calculated internally. In other words, your “dmi/dt” would be “r * v”.
Read the quoted text below carefully to make a sound decision. Quoting text from CFX User Guide:
“Fluid-specific sources are applied directly to fluid as specified and are not multiplied by volume fraction; that is, the sources are assumed to be specified per unit volume of geometry, not per unit volume of the phase. If you have a source expression that is per unit volume of the phase, you must either multiply the source by volume fraction or else use Bulk Sources, which are discussed below.
Fluid-specific sources are not available for equations in homogeneous multiphase flow that span all fluids; Bulk Sources are the only appropriate option for these situations.”
For information about mass sources, please refer the attached screenshot.
September 24, 2018 at 9:00 ammichele rocchiSubscriber
thank you for the clear answer
- You must be logged in to reply to this topic.
Earth Rescue – An Ansys Online Series
The climate crisis is here. But so is the human ingenuity to fight it. Earth Rescue reveals what visionary companies are doing today to engineer radical new ideas in the fight against climate change. Click here to watch the first episode.
Subscribe to the Ansys Blog to get great new content about the power of simulation delivered right to your email on a weekly basis. With content from Ansys experts, partners and customers you will learn about product development advances, thought leadership and trends and tips to better use Ansys tools. Sign up here.
- Suppress Fluent to open with GUI while performing in journal file
- Floating point exception in Fluent
- What are the differences between CFX and Fluent?
- Heat transfer coefficient
- Getting graph and tabular data from result in workbench mechanical
- The solver failed with a non-zero exit code of : 2
- Difference between K-epsilon and K-omega Turbulence Model
- Time Step Size and Courant Number
- Mesh Interfaces in ANSYS FLUENT
- error in cfd post
© 2023 Copyright ANSYS, Inc. All rights reserved.