What are differences between Surface to Surface and Discrete Ordinates models in Ansys Fluent?

 The Surface-to-Surface (S2S) and Discrete Ordinates (DO) models in Ansys Fluent are both used for simulating radiative heat transfer, but they have different approaches and applications:

FLUENT UDFs for Non-Equilibrium Heat Transfer in Porous Media (Two-Energy Model)

FLUENT UDF manual might not explicitly mention using two temperatures together in a single User Defined Function (UDF). However, there are ways to achieve the non-equilibrium heat transfer with a two-energy model using UDFs. Here's how you can approach it:

1. Define UDFs for Source Terms:

Create separate UDFs for the source terms in both the solid and fluid energy equations. In these UDFs, you can access the following information:

• Cell-centered Variables: You can use C_CENTROID(c,t) to get the current time step values for various variables at the cell centroid, including fluid temperature (C_T(c,t)) and other relevant properties.
• Custom User Defined Memory (C_UDM): This allows you to store and access data from previous time steps. You can define separate UDFMs for solid and fluid temperatures from the previous time step (e.g., C_UDM(c,T_SOLID_PREV) and C_UDM(c,T_FLUID_PREV)) and update them within the UDFs.

Ansys Convection Simulation Slowdown: Dropping CPU Usage (Solid-Fluid Interaction)

 "Slowdown During Convection Simulation in Ansys Workbench"

It's a common challenge to experience slowdowns in Ansys simulations, especially for complex problems involving both solid and fluid bodies with convection. Here are some potential reasons why your CPU usage might be dropping and the simulation slowing down:

1. Convergence Issues:

• The most likely culprit is the solver struggling to converge to a solution. As the simulation progresses, the solution might become more complex, requiring smaller timesteps and more iterations to achieve convergence. This can lead to a decrease in CPU utilization as the solver spends more time calculating with smaller steps.

2. Time Stepping Issues:

• The automatic time stepping algorithm might be adjusting to very small steps as the simulation progresses, leading to unnecessary calculations and reduced efficiency.

Ansys Fluent: Validating Printed Circuit Heat Exchanger Model with NIST CO2 and Non-Conformal Mesh

 Validating Printed Circuit Heat Exchanger Model in Ansys Fluent

Here's a breakdown of your questions and some insights to help validate your research paper:

1. NIST Real Gas Model for CO2 in Fluent:

• The error you're encountering with the NIST real gas model for CO2 in Fluent could be due to a few reasons:
• Incorrect File Path: Double-check the path to your CO2 data file ("co2.fld"). Ensure it's located in a directory accessible by Fluent.
• Model Selection: Verify if you've selected "CO2" in the real gas model selection after enabling NIST real gas.
• Software Compatibility: Check the Fluent documentation for compatibility between your Fluent version and the specific NIST real gas model you're trying to use. Some models might require specific versions.

Simulating B-V Equation at Fluid Interface in ANSYS Fluent with UDF

 Directly adding an electric potential at the interface of two fluid domains in ANSYS Fluent isn't possible because the interface itself is a zero-dimensional entity. However, you can achieve a similar effect using a User-Defined Function (UDF) to modify the governing equations and account for the B-V equation at the interface. Here's how you might approach it:

UDF for B-V Equation: