Bulk velocity on parallel lines
Hi all I have a two layer geometry. On the interface for calculation of mass transfer coefficient I need to Reynolds number how that velocity in reynolds relation for any point is bulk velocity of...
View ArticleSolver Issues
Dear Ivar, I am trying to solve 2D Marangoni effect due to solute evaporation. I never succeeded. Therefore I tried a different system in which Marangoni stresses come into play due to temperature...
View Articlephase field
Dear Ivan My name is Konstantinos Karalis and I am a PhD Student at the National Technical University of Athens. I am trying to work with phase field or level set on a ternary fluid system. Do you know...
View ArticleAbsolute tolerance convergence criteria for flow simulations.
Hey. Normally convergence criteria are divided into a relative and an absolute. Where can I find and set the absolute tolerance for my transient flow simulation. Thank you for your time
View ArticleQuestion on heat transport turbulence model
Hi, I am using the Non-Isothermal Flow (nitf) module and I have a question on the heat transport turbulence model. In the equation given by COMSOL, rho * Cp * dT/dt + rho * Cp * u . Grad(T) = Grad . (k...
View ArticleTime dependent fluid problem
Hi I am trying to model a time dependent flow of a newtonian fluid in 2D. The geometry I'm using has sliding walls which cause a flow to be established. The aim of using a time dependent simulation is...
View ArticleLaminar flow module in Comsol 4.3a
Hi, everyone, I am using laminar flow module in Comsol 4.3a to model Navier-Stokes equation. My question is how I should add the body force term F into the equation? The term F is listed in the...
View ArticleBoundary condition in laminar flow, Failed to consistent initial value
Hi any body; I have an static flow at initial time on the solid surface. After t=0; I should exert an external force to the fluid bulk so in this situation my fluid has a motion. Here because the down...
View Articledefining temperature of inlet fluid?
Hi How do I inject a fluid with a required temperature through an inlet? Obviously it's temperature needs to be different from the initial fluid in the model . thanks Dave
View ArticleTemperature change from expansion of air
I am trying to model the flow fields of a fluid (air) traveling through an orifice. I have a working model that works great using only the laminar flow module. However, the viscosity of the fluid is...
View ArticleFluid structure interaction
Hi all! I have some problems simulating a "Fluid structure interaction". I start from this model www.comsol.com/showroom/documentation/model/361/ . I have tosimulate the mitral valve of te heart so l...
View ArticleMarangoni Stirring / Phase Change: Weak Contribution Settings
Hi I have a problem with a weak contribution in a laser surface melting model: My model takes into account solid-liquid phase change using an enthalpy-porosity technique and liquid phase volume forces...
View ArticlePolynomial Issue with User-defined Variables
I have a 2D rectangular geometry that has porosity and permeability values dependent on x-coordinate. Polynomial expressions are used to define the local porosity and permeability. However, COMSOL does...
View ArticleTemperature change from expansion of air
I am trying to model the flow fields of a fluid (air) traveling through an orifice. I have a working model that works great using only the laminar flow module. However, the viscosity of the fluid is...
View ArticleHow to define a mixture of two miscible liquids at the inlet?
Hello, I have a question about how to define a mixture of two miscible liquids (for instance water and ethanol) at the inlet. My 2D geometry is as follows: I have two parallel rectangles (representing...
View ArticleBoundary condition setting problem for electrode
Hi! I am using transport of diluted species to simulate particle movement in discharge but have some problems with the boundary condition setting for the electrode: the electron move towards the...
View Articlephase field
Dear Ivan My name is Konstantinos Karalis and I am a PhD Student at the National Technical University of Athens. I am trying to work with phase field or level set on a ternary fluid system. Do you know...
View ArticleAbsolute tolerance convergence criteria for flow simulations.
Hey. Normally convergence criteria are divided into a relative and an absolute. Where can I find and set the absolute tolerance for my transient flow simulation. Thank you for your time
View ArticleQuestion on heat transport turbulence model
Hi, I am using the Non-Isothermal Flow (nitf) module and I have a question on the heat transport turbulence model. In the equation given by COMSOL, rho * Cp * dT/dt + rho * Cp * u . Grad(T) = Grad . (k...
View ArticleTime dependent fluid problem
Hi I am trying to model a time dependent flow of a newtonian fluid in 2D. The geometry I'm using has sliding walls which cause a flow to be established. The aim of using a time dependent simulation is...
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