{"schema":"pubphys.bundle/1","record":{"author":{"account_ref":null,"orcid":null},"builds_on":[],"content_schema":"pubphys.content.revision/1","content_sha256":"3fc7c3c01db868faa485e8481773710a7f05aaa0892b6096f102cad0c642d505","created":"2026-10-15T23:43:22Z","files":[],"origin":{"assisted_by":[],"kind":"seed"},"parents":["ce59fb6cd812fc05906d0c60a71c75ea22bc686bcf38e7c3ef7010834d98ee7b","f65ad5573805b868449f3e52ead6a433262d6e32c0e5015c17cc573e196f1f62"],"salt":"ff1c132c6d18d59e5f010628f838987ae39e3852ec4cb980e90d722793605882","schema":"pubphys.record/2","site":"pubphys.com","target":null,"type":"revision"},"content":{"answer_type":"mechanism","assisted_by":[],"external_id":"fluid.turbulent-combustion.unconfined-ddt","kind":"well-posed","literature_status":"contested","n":"2","parents":[],"plain":"A flame (deflagration, burning that spreads slower than sound) usually needs walls or obstacles to build up into a detonation. Simulations suggest that strong turbulence alone can do it in open space; does this happen in real gas mixtures, and by what route?","posed_since":"","precise":"For a premixed fuel-air flame (for example stoichiometric $\\mathrm{H_2}$-air or $\\mathrm{CH_4}$-air) in homogeneous isotropic turbulence with no walls or obstacles, determine whether deflagration-to-detonation transition (DDT) occurs, and the threshold in turbulent intensity $u'/S_L$ and integral scale $L/\\delta_L$ ($S_L$ laminar flame speed, $\\delta_L$ laminar flame thickness). Test the proposed route in which the turbulent flame speed exceeds the Chapman-Jouguet deflagration speed (the fastest steady deflagration allowed by conservation laws), so pressure builds up in the flame brush and forms shocks that trigger detonation. An answer is a verified criterion for unconfined DDT as a function of mixture and turbulence.","problem_ref":"f65ad5573805b868449f3e52ead6a433262d6e32c0e5015c17cc573e196f1f62","references":"","settled_by":"Experiments with turbulent premixed flames free of walls and obstacles that observe or exclude DDT at controlled $u'/S_{L}$ and $L$, matched by fully resolved simulations with detailed chemistry.","status_note":"Simulations published in 2019 support the route in which the turbulent flame speed exceeds the Chapman-Jouguet deflagration speed; channel experiments up to 2025 are consistent with it, but no test free of walls and obstacles exists, and only a few mixtures have been tested.","title":"Can turbulence alone turn an unconfined premixed flame into detonation?","topic_ref":null},"content_withheld":"false","files":[],"attested":{"attestation":{"batch":null,"client_id":null,"id_token_sha256":null,"kind":"platform"},"record_hash":"e3d2b6c174b2023c5d485f0f27f2f153d93a06e64dda931420c9f26c3d3250ec","schema":"pubphys.attested/1"},"id_token":null,"id_token_withheld":"false","envelope":{"attested_hash":"827ec5f413e5416358b948cc02fdbc7351a74824767e5cb5792194260d724072","platform_signature":{"key_id":"c6afc19b31429869751f06879c75cd64ea92654423d15b44be775bf1310a60da","sig":"61ZvuPL_UVypcUguXoEu6-aeEb7WQClGMoe324QY_bf8kD1p7MdjF6X7IaYLdn0qwA7exvRcaEAOmaQRI3q2Aw"},"schema":"pubphys.envelope/1"},"ots":{"attested":["AE9wZW5UaW1lc3RhbXBzAABQcm9vZgC_ieLohOiSlAEIgn7F9BPlQWNYuUjMAv28c1GnSCR2fly1eSGUJg1yQHLwIIKToBIgGULWMlUeRFQNjw1bP_xHIoRtDpVzkYtow941CPAgro6m5p50qT4TRfpisdHmz6bX_ji7RWyQUdJDWlk06_wI8SCMqhWH-BEj-8TEHkjmbJaVlHqm8Do6osZ4oAhDM3jdMQjxIGemoraqQWGLXO6v2S5SToZw0vd6TDoBg9XJ_zY2kywrCPAgFOp-xUHNnORjjQ8kMKAJ72j2-svPM72n4mtDdriXttsI8CBGhQttzGNKBcHwTYm54HtQaQHe2dN-Bc40mXhRhUdChwjxIPRhXPPRn9t_0pTcbytoMJBVk7mE9_Tea-UWMyx91Sd_CPEgC07znjc0bVDgPzONkw3aBXeRFcSLeM3BhuNQIWI6mKkI8CCCFfNrg2ZeB51PNa84j-z6Sin0AxT6aP9r7HupgUKbMwjxICknnLxa8xs8qmAdhtb0NnANbtwYyrlRTgqcMVLLl8ogCPEgHd9u6OIGCvUV12A1B1xdiOprSJ-4w0cqwfe7CzVX5HsI8CDQo_sIWZiWXaTGRSQBLmU-lHJKskYKqsjO1r02DhB8LAj_8Ajn9YmozHwo9QjwEJ46aM9ZDv3TdtqV3ZbRsNgI8SBOF8pILGf1kodr5MKmQs6Cd93joraGn3g6UPt_-kewPwjwIOG-gmM7bd_eR4AiDMNfluS3xvr7vicLR-sCBr5qtG2cCPAgrVNFrCoeQcCxhlmnE0BzHgR8HQpZAlfqzDDFzfWb8GUI8QRq0WWT8AjZJ2cF_c7k8ACD3-MNLvkMjiwraHR0cHM6Ly9ib2IuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZ_AI9ZMS1zxd7IEI8BDd00WgJZ0RncsC1Fyai_4aCPEgvxMFrnu7F05IW5INiraQ3OVEYMjNx6JfBxw1Q4jPLi4I8QRq0WWS8Ag2zxPAtI5JsP8Ag9_jDS75DI4uLWh0dHBzOi8vYWxpY2UuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZwjxIHAnv4KFFf4uiYEFJvLxiMxSyz8VowJP4roTfDD9h7bICPAgj5tgvbNF7mxSP4jGGE66ezUFRLnI4g1VTkvuV4VtCPAI8CCxlc1HuKORuHgn7DYIYcDhc4oo99OkTWBEvddBypoa7AjwIFcjjaF8kDNDYCZGaNISlRjvX-I7in-QNwsr4JYQbFJvCPAgnl0k4gs7LuY5i1umiHO-J7My3uBThLJUWQoY9LdVSrQI8SA6-Ft11_K_GqMNWYhkVsVqCFvXSYbp4S8JoLsLBnUzvgjxIBC8_mAE7JBP35SNxDBcG7joLJwURpMxdV2vSO64_jEOCPEge04Coj1xSi7CE8UwqiBGNhPyZ5QdD_YZwn-heSdObU4I8SBgdDSgr3VUx1j8m_pK7-OzMwwFgXeLy43ujffCv-hf5AjwIMl-PnAt4xjoBEVU4-nkyN0NKRa9AvX4kEMfllFyIJS9CPFZAQAAAAHz4rV-uwQFg02bVnEMUFgpIdGKjM4tWuID1kTVnrjisAAAAAAA_v___wJURAIAAAAAABYAFBFys2oc0-U-bYrC3VulGLzND5fbAAAAAAAAAAAiaiDwBHLTDgAICPEgMJIBYi46xOIuFDwzJ9nOx14ngW5HbglUf65ORpkoIYcICPAgHgGWEGCDHWgscwT92NOoJ7s-ezbPkyiWr2RnYZDC_dwICPAgtffMyyLu-MscJsDc0dzwGspwSrrmvVAnMNgsgWhHClgICPAgMUl1OfBDUwhp5VZjHwVA0nuz1F5HZTUJCHAnM1L1F3MICPAgStK7UWpnrUueV5EaE7uE0y6BLMp6EANmrbhrTqEBZu8ICPAg5LVW7IHtUL5mNOvPx1hOTfLMmqlQ7t9EFW-KDtrISIQICPAgABgXZ6upFU8qiDQKFtQFpqkjKwl0PsxM4JUjVLlDKbkICPAgEwb96FiOhjlbwI8GFZQ4a5GXwxs4bUdqVOMKrtBWV30ICPEgqBg-wp0c8CAPV9k6J7wIa9_GtQfpWmhpE1zqFZyi2pQICPAg2pZLTVPGJbriiz0UhMytYDVYAXOgQnWDcrMOewK9O8cICPEgxm3QwzbvT4siJzubQGnST67bWv-exYwSPP1KDi7CaUwICPEgm6udUudfjUaM0gUFTylKGDMypj7ptMTG0zmxd_T5yTcICPAgMpOInkjFCVp1pOZhfZnyPAl8hdWGmHzQcrGLgLwSKLgICAAFiJYNc9cZAQPzpjs"],"envelope":["AE9wZW5UaW1lc3RhbXBzAABQcm9vZgC_ieLohOiSlAEIJB05pWwg-DxR8CCVxr8pPhAvCtDUm2oW5DRzYnuHNSDxICQHVcQCLfJavN7LONyJcfj3buPaSuUqFfLE1cN3GYddCPEgvShfOXdXz2JUKYQ5-kC4KrSGUQWppZVC6ix02pPKFk0I8CAOUMjGxxLkbLfhad5BZzeaZyFnvA_6qoOB-j53JAyjDQjxIExDoCYDabkhJ4K_EvUuKOA9wNIF9BNip82iNBMzCMp8CPAgVYjhavNiqjjs8Q0LHXE9dncIfyYgqp1m4TggBZcCsIYI8SClehk4kg242izhJrq_E_tagve9Vmc9VZxesxsdo1-l-gjxIACQj7hTnt3eJLkSmDJTNTyOSwO3o1e3cI0C3xqbxiWlCPEgbfsqNEiKd31vqHmWLbVpOwfRJ_Z2YUckwYh0fQRhz9sI8SCHI26f1bMr-H5VtXG_HgMHDd8PPImPLhsWPB8PPaY3jwjwIKD8mGRUgbk2Dt1xG-4OxMpCuw1ya5UEUQXsqASURGCtCPAgkPXX-naXR0fRIdS-sEDlzYmtMvSCNH42ESUF0QXb6NUI8CDQo_sIWZiWXaTGRSQBLmU-lHJKskYKqsjO1r02DhB8LAj_8Ajn9YmozHwo9QjwEJ46aM9ZDv3TdtqV3ZbRsNgI8SBOF8pILGf1kodr5MKmQs6Cd93joraGn3g6UPt_-kewPwjwIOG-gmM7bd_eR4AiDMNfluS3xvr7vicLR-sCBr5qtG2cCPAgrVNFrCoeQcCxhlmnE0BzHgR8HQpZAlfqzDDFzfWb8GUI8QRq0WWT8AjZJ2cF_c7k8ACD3-MNLvkMjiwraHR0cHM6Ly9ib2IuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZ_AI9ZMS1zxd7IEI8BDd00WgJZ0RncsC1Fyai_4aCPEgvxMFrnu7F05IW5INiraQ3OVEYMjNx6JfBxw1Q4jPLi4I8QRq0WWS8Ag2zxPAtI5JsP8Ag9_jDS75DI4uLWh0dHBzOi8vYWxpY2UuYnRjLmNhbGVuZGFyLm9wZW50aW1lc3RhbXBzLm9yZwjxIHAnv4KFFf4uiYEFJvLxiMxSyz8VowJP4roTfDD9h7bICPAgj5tgvbNF7mxSP4jGGE66ezUFRLnI4g1VTkvuV4VtCPAI8CCxlc1HuKORuHgn7DYIYcDhc4oo99OkTWBEvddBypoa7AjwIFcjjaF8kDNDYCZGaNISlRjvX-I7in-QNwsr4JYQbFJvCPAgnl0k4gs7LuY5i1umiHO-J7My3uBThLJUWQoY9LdVSrQI8SA6-Ft11_K_GqMNWYhkVsVqCFvXSYbp4S8JoLsLBnUzvgjxIBC8_mAE7JBP35SNxDBcG7joLJwURpMxdV2vSO64_jEOCPEge04Coj1xSi7CE8UwqiBGNhPyZ5QdD_YZwn-heSdObU4I8SBgdDSgr3VUx1j8m_pK7-OzMwwFgXeLy43ujffCv-hf5AjwIMl-PnAt4xjoBEVU4-nkyN0NKRa9AvX4kEMfllFyIJS9CPFZAQAAAAHz4rV-uwQFg02bVnEMUFgpIdGKjM4tWuID1kTVnrjisAAAAAAA_v___wJURAIAAAAAABYAFBFys2oc0-U-bYrC3VulGLzND5fbAAAAAAAAAAAiaiDwBHLTDgAICPEgMJIBYi46xOIuFDwzJ9nOx14ngW5HbglUf65ORpkoIYcICPAgHgGWEGCDHWgscwT92NOoJ7s-ezbPkyiWr2RnYZDC_dwICPAgtffMyyLu-MscJsDc0dzwGspwSrrmvVAnMNgsgWhHClgICPAgMUl1OfBDUwhp5VZjHwVA0nuz1F5HZTUJCHAnM1L1F3MICPAgStK7UWpnrUueV5EaE7uE0y6BLMp6EANmrbhrTqEBZu8ICPAg5LVW7IHtUL5mNOvPx1hOTfLMm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