Dear Denaro

I agree with you, as the smoke of the cigarette not affect by the pressure force from the high amount of the flow but the major parameter is the change of the density, so there is no transition and turbulent flow in this case as that depends on Reynolds number.

Do you have any method to compare between numerical and experimental work?

I suppose that a particle-tracing is supplied in Fluent. However, it is very simple to implement the method, since it is based on the solution of the lagrangian equations dx/dt = v.

However, if you work for a steady laminar flow problem, there is no difference between stream-lines and smoke-lines.

I agree with Filippo Maria Denaro: smoke particles are so small and so disperse (see, e.g. paper attached) that their presence does not alter the flow.

So another option would be to solve a convection-diffusion problem, where the Navier-Stokes equations are solved (with variable density that depends on the temperature) and a scalar quantity (solid fraction) is convected with the resulting flow.

The diffusion part would be present if there were unresolved turbulent scales for which some model would need to be added. If you can afford DNS, then molecular diffusion is probably negligible. Check out 'Species Transport Equations' from Fluent.

I think all these elements should be available in many other CFD codes too.

http://www.sciencedirect.com/science/article/pii/S0021850214000627

Cigarette flow is not simply laminar flow. Under normal circumstances it has laminar, transient and turbulent regions of flow. Following CFD software can be used for your analysis and simulation purposes:

ANSYS CFD, COMSOL and if you want to use browser based platform then try simscale. https://www.simscale.com.

Regards

Saad Sharjeel

Study the density values and velocity time flow directions to know the flow is laminar

Thank you all for the answers

Dear @ Saad The turbulent flow means the fluid has very high velocity but the smoke of the cigarette has a very low velocity so it turbulence fluid and not turbulent flow.

Dear Ghassan,

turbulence is a state in a flow, not a property of a fluid. Smoke of cigarette highlights the transition from laminar to turbulent state, depending on the increasing local Reynolds number.

However, smoke-line is a nomenclature that has no necessarily a link to turbulence, it exists also in laminar conditions.

Dear Denaro

I agree with you, as the smoke of the cigarette not affect by the pressure force from the high amount of the flow but the major parameter is the change of the density, so there is no transition and turbulent flow in this case as that depends on Reynolds number.

Hi dear Ghassan

I think you can simulate in fluent and done particle tracking section

@Ghassan, please go through the link below, it will clarify much of your confusion,

http://profs.sci.univr.it/~zuccher/research/blstability/

Regards.

Saad Sharjeel

Dear Ghassan, smoke simulation is a classic problem in CFD. See this seminal paper (in particular figure at pag.163) and its divulgative version. A simulation program should resolve Navier-Stokes equations and (in laminar case) trace streamlines. Gianluca

interesting question  

Dear Ghassan,

As for me, I think the problem is to simulate a pure plume flow from isolated source (classification of Turner); i.e. intrusion of a fluid into an ambient at rest.

It is important to identify several points:

- medium: do you consider an infinite medium or a confined (semi-confined). It is too important as far as you may have a boundary condition issue. Here is a work we perform on the issue of outlet bc for example (not too close to what you aim maybe but you can take a look)

https://www.researchgate.net/publication/319547102_Large_eddy_simulations_of_an_air-helium_buoyant_jet_in_a_two_vented_enclosure_influence_of_the_outlet_boundary_condition?_iepl%5BviewId%5D=8E9AIOfdjjDFPtiLMvfMl18y&_iepl%5BprofilePublicationItemVariant%5D=default&_iepl%5Bcontexts%5D%5B0%5D=prfpi&_iepl%5BtargetEntityId%5D=PB%3A319547102&_iepl%5BinteractionType%5D=publicationTitle

- approximation: Boussinesq or Low Mach Number

- source conditions: continuous (plume) or not-continuous (thermal puff)

Note: buoyant accelerations can induce turbulence upstream (Re increase upstream)....

I simulated using the TRUST TrioCFD. French code for the CEA.

Conference Paper Large eddy simulations of an air-helium buoyant jet in a two...

Nice answer Dr Guillermo Casas González.

Regards!