5 questions we ask before preparing a CFD consulting quote

This post was created based on the expert advice of PADT CFD engineer and Project Lead, Nathan Huber.

Simulating the behavior of liquids and gases has become a standard part of product development in products where fluid behavior plays an important role.  Here at PADT, we have been using Computational Fluid Dynamics, or CFD, for years to model everything from combustion in turbine engines to cooling of electronics, to golf balls. With that experience, our estimates for a given project have become reasonably accurate.

However, we can only estimate accurately if we have complete and accurate information on what you need simulated and what you hope to gain from the simulation. To help everyone arrive at more accurate cost and schedule estimates, even if you are planning a project internally, we offer the following list of five questions we always ask:

1: Have we signed a Non-Disclosure Agreement (NDA)?

Before we can do anything, we need to have an agreement in place that clearly defines how both sides handle proprietary information.  When we have tried holding meetings to gather information for a quote before an NDA is in place, we almost always waste time. There is just too much that is proprietary in most products.

2. What does your CAD Geometry look like?

We also need to know the physical geometry of your system.  That is why we ask for an accurate and complete CAD model.  We take some time to poke through the files in our software to make sure we can use the geometry, it is accurate, and it has the level of detail required for CFD. Basically, we check to see if we can pull a fluid domain from your CAD models. Remember, we are not simulating the solid part of your product; we are modeling the inverse and therefore need to pull a negative volume from your geometry.

3. What are the Boundary Conditions and Material Properties?

Now that the geometric domain is understood, we need to know what is inside that domain, and what is acting upon it.  We will ask you for boundary conditions, and for the material properties of the fluid or fluids you are asking us to model.  The complexity, time variation, and severity of the loads drive the difficulty of setting up and running the simulation. And the material properties can also impact the sophistication of the model as well as its robustness.  Both, therefore, have a significant impact on cost.

4. What results do you want to see?

When a simulation finishes, it can be post-processed to get a vast array of plots, figures, animations, pretty pictures, etc.  Those take time to create, so we need to know what you want to see. Also, we set up some post-processing parameters before we start the simulation.

5. What do you want to learn from your CFD Simulation?

The whole point of doing a CFD simulation is to study the behavior of your system. We need to know what behavior you need to understand so we can make sure that the simulation we propose answers your questions and guides you in your design process. 


We hope you find this review useful when you are planning your internal CFD project as well as those you outsource. And speaking of outsourcing, please consider PADT as your resources for any future simulation projects of any type, not just CFD.  Now, you already know what questions we will ask.

Fluids Innovations in ANSYS 2019 R3 – Webinar

Products such as ANSYS Fluent, CFX, and Ensight work together in a constantly improving tool kit that is developed to provide ease of use improvements for engineers simulating fluid flows and the impact those flows have on physical models. 

Fluids simulation users will find that ANSYS 2019 R3 includes many enhancements that further simplify the user experience and broaden use to new applications. The new Fluent experience has been improved so you can enjoy more CFD in less time, with less training.

Join PADT’s Simulation Support and Application Engineer, Sina Ghods, for a look at what is new and improved for fluids simulation tools in ANSYS 2019 R3. This presentation includes updates regarding: 

  • Usability Enhancements
  • Watertight Geometry Workflow
  • TurboGrid & BladeEditor
  • Meshing Enhancements
  • And many more innovative capabilities

Register Here

If this is your first time registering for one of our Bright Talk webinars, simply click the link and fill out the attached form. We promise that the information you provide will only be shared with those promoting the event (PADT).

You will only have to do this once! For all future webinars, you can simply click the link, add the reminder to your calendar and you’re good to go!

ANSYS Discovery Live – Fluid Flows Webinar Recording & FAQ

Below you can find some of the most frequently asked questions from this webinar, along with our answers.

Q: What computer and license type are you actually using for running the simulation? Ram, cores, CPU, etc.

A: 16 GB RAM Intel i7, NVIDIA Quadro K1100M

Q: Is the solver running a transient solution in the background while you are post processing and haven’t paused it, or is it marching towards better convergence of a steady state solution?

A: The solver is running a transient solution the entire time. The only time it is not doing this is if I pause the simulation.

Q: Does this require 3D models to be built within Discovery Live, or it can import outside 3D models (Solidworks etc) and still allows the user to add/modify geometry objects on the fly within Discovery Live?

A: Yes, you can import any CAD native format or neutral format in Discovery Live. You can also create Geometry from scratch in Discovery Live using the SpaceClaim tools.

Q: It looks like when you change the “speed – fidelity” setting, the solver resets; while when you change other settings (like domain geometry), the solution continues from last step. What’s being changed when you change the “speed-fidelity” setting?

A: When you change the Speed-Fidelity setting, the computational grid of the domain is coarsened or refined. It is also re-partitioned/parallelized on the GPU cores.

Q: Are there predictive features of simulation, obtaining design suggestions from the end results? Are there inputs for end results to accomplish reverse engineering?

A: Yes, in a sense. Because Discovery Live provides literally “real-time” feedback on design changes, you have design suggestions based on the end results. For reverse engineering in Discovery Live: there are not inputs for end results, but the part you’d like to reverse engineer can be imported (or created) in Discovery Live, and then analyzed in the range of operating conditions to understand it’s performance.

Q: Do you have any control of the mesh? How boundary/layer effects can be checked?

A: Control of the mesh available via the Speed-Fidelity slider bar. Boundary layer effects could be checked using surface integrals of force, but again recall that if you’re trying to finely resolve details such as boundary layer physics, you may need to consider the next level of accuracy which would be Discovery AIM or Fluent.

If you have any other questions, feel free to contact us at sales@padtinc.com or contact PADT’s CFD Team Lead Application Engineer Clinton Smith at clinton.smith@padtinc.com.