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Old   May 28, 2020, 03:27
Default How to use MAT_ALE_MIXING_LENGTH in LS-DYNA?
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master ma
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Hello everyone, i encountered some problem while using LS-DYNA, hope get some help here.

Some background : I need to use ALE module in LS-DYNA to simulate air flowing around rigid body, for example air flows around a cylinder. There is not any turbulent model can be chosen, only inviscid or laminar flow. But I saw a material “MAT_ALE_MIXING_LENGTH” in keyword, and hope it can be used to modify fluid turbulence viscosity near wall.

In LS-DYNA KEYWORD USER'S MANUAL, it described MAT_ALE_MIXING_LENGTH can be used to simulate fluid. However, dyna manual, both User’s Manual and Theory Manual, did not further describe how to use this mat.
For example:
Problem 1. In this MAT_ALE_MIXING_LENGTH, “Internal flow mixing length polynomial coefficients” and “External flow mixing length polynomial coefficients” need to be filled. HOW does LS-DYNA ALE SOLVER make a distinction between inside flow and outside flow?
Problem 2. In many fluid dynamic problem, fluid turbulence viscosity near wall need to be calculate. HOW does LS-DYNA ALE SOLVER know the distance between fluid cell and wall (whether wall is represented by shell element or SPC).
Problem 3. I try to use this mat anyway, error “glibc detected ………. free():invalid next size …….” appear in the beginning of simulation. Does other keywords need to be used, when I want to use “MAT_ALE_MIXING_LENGTH” ?
Problem 4. In LS-DYNA User’s Manual, MAT_ALE_MIXING_LENGTH only mentioned in MAT. In Theory Manual, there is no description relate to MAT_ALE_MIXING_LENGTH at all. SO does this MAT can be used at all? I mean if this keyword only added in MAT library and did not add in ALE SOLVER yet?
Problem 5. Is there any way to model turbulent flow in DYNA ALE SOLVER?

This problem bug me for some time, thanks a lot for your help!
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ale, ls-dyna, mat_ale_mixing_length

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