Orca 3D CFD


Let’s say I have a N channels each with N apertures for bubble development. Can the channels and apertures be meshed and modeled by Orca 3D CFD?

I have some experience with OpenFOAM. Although there is a DTChull tutorial, doing a hull analysis for my boat will be over my head. Still, I have done jet boat nozzle analysis, flow around a cylinder analysis, and have experience with snappyHex meshing. I know, for example, that mesh is very important for foundation of CFD analysis. If the mesh is garbage, the results are garbage.

I watched an hour long introduction to Orca 3D CFD. I was really impressed with the benchmarks. With that said, the benchmarks were for external boat hulls. Does the automatic meshing mesh closed channels with apertures if they exist. Is the meshing accurate with channels and apertures? I know meshing can become more difficult for complex geometries and sharp corners. Also, I noticed Orca 3D CFD is automated, which is nice. Still, is it possible to dig into the solver settings and mesh manually?

If I had time, I would finish my OpenFOAM path of studying mathematics, advanced fluid mechanics, CFD, and OpenFOAM. That was my original path to keep me busy. I am a retired chemical engineer. Then, my brother, who races jet boats as a hobby, works on jet boats as a hobby, and optimizes the bottom of the boat for speed on his own through machining and manipulation, asked me to help him start a jet boat building business. I would like to model bubble development to reduce drag by interrupting the boundary layer. With that said, I want to test it with Orca CFD first. Is this possible? It would take me years to learn the OpenFOAM the way I need to, which would include advanced C++ Object Oriented Programming. I have 3 months.

I currently have ORCA on my system sans the CFD. I engaged the team at ORCA to run a running strake analysis on the attached boat. We executed four runs: without strakes, with strakes parallel to the LWL, with strakes along buttock line and finally with strakes along the diagonal. The point of this story is that ORCA/Semerics CFD analysis easily sensed the difference between the various strake configurations, all of which are of course quite sharp at their edges. I can only assume that the automated meshing is in fact very accurate.

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Contact the folks at Orca3D and ask if the CFD version they provide is capable of modeling bubble development and motion.

Drag reduction by air injection into the boundary layer has been studied numerous times in the past. You might want to review some of the previous work.

Thanks for your feedback, and beautiful boat. I am learning and just curious. Did you use streamlines to position your strakes?

Part of my concern are the channel, pipe chine, and aperture. In SnappyHex mesh–OpenFOAM–one chooses inside or outside to mesh in the cases that I am familiar with. This is a coordinate point. For example, the nozzle I did needed to be meshed on the inside for fluid flow. I had to specify a point on the inside to make sure it didn’t mesh on the outside.

In my idea, which is only an idea, there will be an opening to a pipe chine that is open to the atmosphere after the boat is planing. The n channels intersect the chine pipe from an area in the bottom of the boat to another area on the bottom of the boat on both sides of the keel. The apertures will be N in number from near the keel to chine and on the stern side.This is where bubbles “might” exit. The pipe chine, channels, and apertures would have to be meshed along with the outside of the boat automatically.

I assume skewness and non-orthogonal meshing abnormalities will occur. This can affect numerical diffusion and complicate values such as bubble development–the mathematics. So, I am curious if the automatic meshing would handle all this on it’s own? If not, can it be done manually in Orca 3D CFD?

Now, I know the chine and channels will initially fill with water. I hypothesize that the velocity of water flowing over the apertures will create a lower pressure than the opening of the pipe chine that will then be exposed to direct air flow as the boat is planing. This could move the water from the channels through the aperture and make room for air flow and bubble formation. I believe it is a long shot, and I would like to test it with CFD. It is just a newbie idea.

My brother races jet boats. In fact, he has won the World Championship Jet Boat Marathon twice, placed second three times, and placed third three times. He travels at speeds greater than 111 MPH. He optimized the bottom of the boat for racing. He also works on the engines as he is an automotive technician that owns his own 10 man shop. He is starting a jet boat building business. He asked me to look into software,. learn the software, and teach him when he has the time. I am a retired chemical engineer. I was brainstorming on Saturday, as I know a little about fluid mechanics, and I came up with the above idea. I need to practice the software, and I would like to try it out in various configurations of course.


Yes, I have read some abstracts, and I plan to purchase the journal articles. It has been shown to work with large bubbles. I appreciate your feedback. I have contacted Orca 3D CFD.

Orca3D Marine CFD, based on the SimericsMP software, will automatically mesh the inside of tubes as well as the outside of the hull. I will respond to your email request with a short video showing a planing hull with ventilation pipes.

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Thank you for commenting. You are always very reactive and forthcoming. Obviously, you are very knowledgeable. I appreciate the e-mail.

I have not done an extensive literature review but I did find [1], and [1] has references. I didn’t consider that this might be patented. So, I need to read more than [1], and I need to check for patents. To me, it seems to be common knowledge although the structure might be novel. It is the same bubble formation principle as jacuzzi bubble formation. Still, I thank you for your insight!

According to [1], drag reduction is remarkable. Still, one has to get the structure correct. I am glad Orca 3D CFD will mesh the internal and external geometry automatically. By the way, I was really impressed with the greater than hour long presentation with example of Orca 3D CFD use and benchmarks.Nice product.


[1] Verschoof, Ruben A; van der Veen, Roeland CA; Sun, Chao; Lohse, Detief. (2016). Bubble drag reduction requires large bubbles. URL: [1606.06471] Bubble drag reduction requires large bubbles

As someone that tested multiple CFDs solutions, including OpenFOAM, none was so straight forward and easy to setup as Orca’s. And when the trouble arrived, the team was ready to help as always.

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I am interested in modeling the flow of water over a reef as waves pass over. It’d be nice to model the breaking of the wave, but not required. Would like to calculate the force on individual corals on the reef, that protrude up into the flow.

Also, if the reef is porous, flow through the channels.

Potentially a doable thing with ORCA3D CFD? I know I can do it with OpenFOAM.

Yes, I think so (it would require the Premium version since there are waves). Is the level of porosity limited to the channels between the coral branches, or do you also want to treat the branches themselves as porous? And I assume these are hard coral, not moving in the flow? If you have a Rhino model that is entirely closed polysurfaces or meshes, I could try meshing it in Orca3D Marine CFD. Contact me at support@orca3d.com.

Another thought is to use Darcy’s law to model the porosity if the problem becomes too large to solve with individual cells. We have a user who did that recently when modeling the flow of salt spray through commercial crab pots on the deck of a fishing boat, as part of a study on ice accretion.

The corals are solids, as is the reef, but there are channels through the solids. So no need to model the structures themselves as percentage material (rubble pile).

The dream is we model soft corals, so they would move with the flow. A big ask, I know. :slight_smile:

I will send a simple model…